Using Packages

Many Linux distributions have some sort of package installation system, such as RPM. This can assist in setting up a standard configuration, but if you need to have a different set of features (such as a secure server, or a different database driver), you may need to build PHP and/or your webserver. If you are unfamiliar with building and compiling your own software, it is worth checking to see whether somebody has already built a packaged version of PHP with the features you need.

Using Packages

There are a few pre-packaged and pre-compiled versions of PHP for Mac OS X. This can help in setting up a standard configuration, but if you need to have a different set of features (such as a secure server, or a different database driver), you may need to build PHP and/or your web server yourself. If you are unfamiliar with building and compiling your own software, it's worth checking whether somebody has already built a packaged version of PHP with the features you need.

Compiling for OS X server

There are two slightly different versions of Mac OS X, client and server. The following is for OS X Server.

Compiling for MacOS X client

Those tips are graciously provided by Marc Liyanage.

The PHP module for the Apache web server included in Mac OS X. This version includes support for the MySQL and PostgreSQL databases.

NOTE: Be careful when you do this, you could screw up your Apache web server!

Do this to install:

1. Open a terminal window.

2. Type wget http://www.diax.ch/users/liyanage/software/macosx/libphp4.so.gz, wait for the download to finish.

3. Type gunzip libphp4.so.gz.

4. Type sudo apxs -i -a -n php4 libphp4.so

5. Now type sudo open -a TextEdit /etc/httpd/httpd.conf. TextEdit will open with the web server configuration file. Locate these two lines towards the end of the file: (Use the Find command)

   #AddType application/x-httpd-php .php #AddType application/x-httpd-php-source .phps

   Remove the two hash marks (#), then save the file and quit TextEdit.

6. Finally, type sudo apachectl graceful to restart the web server.

PHP should now be up and running. You can test it by dropping a file into your Sites folder which is called test.php. Into that file, write this line: <?php phpinfo() ?>.

Now open up 127.0.0.1/~your_username/test.php in your web browser. You should see a status table with information about the PHP module.

Using Binary Packages

Using binary packages to install PHP on OpenBSD is the recommended and simplest method. The core package has been separated from the various modules, and each can be installed and removed independently from the others. The files you need can be found on your OpenBSD CD or on the FTP site.

The main package you need to install is php4-core-4.3.3.tgz, which contains the basic engine (plus gettext and iconv). Next, take a look at the module packages, such as php4-mysql-4.3.3.tgz or php4-imap-4.3.3.tgz. You need to use the phpxs command to activate and deactivate these modules in your php.ini.

# pkg_add php4-core-4.3.3.tgz
# /usr/local/sbin/phpxs -s
# cp /usr/local/share/doc/php4/php.ini-recommended /var/www/conf/php.ini
  (add in mysql)
# pkg_add php4-mysql-4.3.3.tgz
# /usr/local/sbin/phpxs -a mysql
  (add in imap)
# pkg_add php4-imap-4.3.3.tgz
# /usr/local/sbin/phpxs -a imap
  (remove mysql as a test)
# pkg_delete php4-mysql-4.3.3
# /usr/local/sbin/phpxs -r mysql
  (install the PEAR libraries)
# pkg_add php4-pear-4.3.3.tgz

Read the packages(7) manual page for more information about binary packages on OpenBSD.

Using Ports

You can also compile up PHP from source using the ports tree. However, this is only recommended for users familiar with OpenBSD. The PHP 4 port is split into two sub-directories: core and extensions. The extensions directory generates sub-packages for all of the supported PHP modules. If you find you do not want to create some of these modules, use the no_* FLAVOR. For example, to skip building the imap module, set the FLAVOR to no_imap.

Common Problems

• The default install of Apache runs inside a chroot(2) jail, which will restrict PHP scripts to accessing files under /var/www. You will therefore need to create a /var/www/tmp directory for PHP session files to be stored, or use an alternative session backend. In addition, database sockets need to be placed inside the jail or listen on the localhost interface. If you use network functions, some files from /etc such as /etc/resolv.conf and /etc/services will need to be moved into /var/www/etc. The OpenBSD PEAR package automatically installs into the correct chroot directories, so no special modification is needed there. More information on the OpenBSD Apache is available in the OpenBSD FAQ.

• The OpenBSD 3.4 package for the gd extension requires XFree86 to be installed. If you do not wish to use some of the font features that require X11, install the php4-gd-4.3.3-no_x11.tgz package instead.

Older Releases

Older releases of OpenBSD used the FLAVORS system to compile up a statically linked PHP. Since it is hard to generate binary packages using this method, it is now deprecated. You can still use the old stable ports trees if you wish, but they are unsupported by the OpenBSD team. If you have any comments about this, the current maintainer for the port is Anil Madhavapeddy (avsm at openbsd dot org).

Required software

Solaris installs often lack C compilers and their related tools. Read this FAQ for information on why using GNU versions for some of these tools is necessary. The required software is as follows:

• gcc (recommended, other C compilers may work)

• make

• flex

• bison

• m4

• autoconf

• automake

• perl

• gzip

• tar

• GNU sed

Using Packages

You can simplify the Solaris install process by using pkgadd to install most of your needed components.

Apache Module Quick Reference

PHP can be compiled in a number of different ways, but one of the most popular is as an Apache module. The following is a quick installation overview.

1.  gunzip apache_1.3.x.tar.gz
2.  tar xvf apache_1.3.x.tar
3.  gunzip php-x.x.x.tar.gz
4.  tar xvf php-x.x.x.tar
5.  cd apache_1.3.x
6.  ./configure --prefix=/www
7.  cd ../php-x.x.x
8.  ./configure --with-mysql --with-apache=../apache_1.3.x --enable-ftp
9.  make
10. make install
11. cd ../apache_1.3.x
12. ./configure --activate-module=src/modules/php4/libphp4.a
13. make
14. make install
15. cd ../php-x.x.x
16. cp php.ini-dist /usr/local/lib/php.ini
17. Edit your httpd.conf or srm.conf file and add: 
      AddType application/x-httpd-php .php

18. Use your normal procedure for restarting the Apache server. (You must
    stop and restart the server, not just cause the server to reload by
    use a HUP or USR1 signal.)

Building

When PHP is configured, you are ready to build the CGI executable. The command make should take care of this. If it fails and you can't figure out why, see the Problems section.

Windows InstallShield

The Windows PHP installer is available from the downloads page at http://www.php.net/downloads.php. This installs the CGI version of PHP and, for IIS, PWS, and Xitami, configures the web server as well.

Install your selected HTTP server on your system and make sure that it works.

Run the executable installer and follow the instructions provided by the installation wizard. Two types of installation are supported - standard, which provides sensible defaults for all the settings it can, and advanced, which asks questions as it goes along.

The installation wizard gathers enough information to set up the php.ini file and configure the web server to use PHP. For IIS and also PWS on NT Workstation, a list of all the nodes on the server with script map settings is displayed, and you can choose those nodes to which you wish to add the PHP script mappings.

Once the installation has completed the installer will inform you if you need to restart your system, restart the server, or just start using PHP.

Manual Installation Steps

This install guide will help you manually install and configure PHP on your Windows webserver. The original version of this guide was compiled by Bob Silva, and can be found at http://www.umesd.k12.or.us/php/win32install.html. You need to download the zip binary distribution from the downloads page at http://www.php.net/downloads.php.

PHP 4 for Windows comes in three flavours - a CGI executable (php.exe), a CLI executable (sapi/php.exe) and some other SAPI modules:

The following steps should be performed on all installations before any server specific instructions.

• Extract the distribution file to a directory of your choice, c:\ is a good start. The zip package expands to a foldername like php-4.3.1-Win32 which is assumed to be renamed to php. For the sake of convenience and to be version independent the following steps assume your extracted version of PHP lives in c:\php. You might choose any other location but you probably do not want to use a path in which spaces are included (for example: C:\Program Files\PHP is not a good idea). Some web servers will crash if you do. The structure of your directory you extracted the zip file will look like:

c:\php
   |
   +--cli
   |  |
   |  |-php.exe           -- CLI executable - ONLY for commandline scripting
   |
   |
   +--dlls                -- support dlls for extensions --> Windows system directory
   |  |
   |  |-expat.dll
   |  |
   |  |-fdftk.dll
   |  |
   |  |-...
   |
   +--extensions          -- extension dlls for PHP
   |  |
   |  |-php_bz2.dll
   |  |
   |  |-php_cpdf.dll
   |  |
   |  |-..
   |
   +--mibs                -- support files for SNMP
   |
   |
   +--openssl             -- support files for Openssl
   |
   |
   +--pdf-related         -- support files for PDF
   |
   |
   +--sapi                -- SAPI dlls
   |  |
   |  |-php4apache.dll
   |  |
   |  |-php4apache2.dll
   |  |
   |  |-php4isapi.dll
   |  |
   |  |-..
   |
   |-install.txt
   |
   |-..
   |
   |-php.exe              -- CGI executable
   |
   |-..
   |
   |-php.ini-dist
   |
   |-php.ini-recommended
   | 
   |-php4ts.dll           -- main dll --> Windows system directory
   | 
   |-...

The CGI binary - c:\php\php.exe -, the CLI binary - c:\php\cli\php.exe -, and the SAPI modules - c:\php\sapi\*.dll - rely on the main dll c:\php\php4ts.dll. You have to make sure, that this dll can be found by your PHP installation. The search order for this dll is as follows:

• The best bet is to make php4ts.dll available, regardless which interface (CGI or SAPI module) you plan to use. To do so, you have to copy this dll to a directory on your Windows path. The best place is your Windows system directory:

  C:\Windows\System for Windows 9x/ME

  C:\WINNT\System32 for Windows NT/2000 or C:\WINNT40\System32 for NT/2000 server

  C:\Windows\System32 for Windows XP

  If you plan to use a SAPI module from c:\php\sapi and do not like to copy dlls to your Windows system directory, you have the alternative choice to simply copy php4ts.dll to the sapi folder of your extracted zip package, c:\php\sapi.

• The next step is to set up a valid configuration file for PHP, php.ini. There are two ini files distributed in the zip file, php.ini-dist and php.ini-recommended. We advise you to use php.ini-recommended, because we optimized the default settings in this file for performance, and security. Read this well documented file carefully and in addition study the ini settings and set every element manually yourself. If you would like to achieve the best security, then this is the way for you, although PHP works fine with these default ini files. Copy your chosen ini-file to a directory where PHP is able to find and rename it to php.ini. By default PHP searches php.ini in your Windows directory:

  On Windows 9x/ME/XP copy your chosen ini file to your %WINDIR%, which is typically C:\Windows.

  On Windows NT/2000 copy your chosen ini file to your %WINDIR% or %SYSTEMROOT%, which is typically C:\WINNT or C:\WINNT40 for NT/2000 servers.

• If you're using NTFS on Windows NT, 2000 or XP, make sure that the user running the webserver has read permissions to your php.ini (e.g. make it readable by Everyone).

The following steps are optional.

• Edit your new php.ini file. If you plan to use OmniHTTPd, do not follow the next step. Set the doc_root to point to your webservers document_root. For example:

  doc_root = c:\inetpub // for IIS/PWS doc_root = c:\apache\htdocs // for Apache

• Choose which extensions you would like to load when PHP starts. See the section about Windows extensions, about how to set up one, and what is already built in. Note that on a new installation it is advisable to first get PHP working and tested without any extensions before enabling them in php.ini.

• On PWS and IIS, you can set the browscap configuration setting to point to: c:\windows\system\inetsrv\browscap.ini on Windows 9x/Me, c:\winnt\system32\inetsrv\browscap.ini on NT/2000, and c:\windows\system32\inetsrv\browscap.ini on XP.

Following this instructions you are done with the basic steps to setup PHP on Windows. The next step is to choose a webserver and enable it to run PHP. Installation instructions for the following webservers are available:

• .. the Windows server family, Personal Web server (PWS) 3 and 4 or newer; Internet Information Server (IIS) 3 and 4 or newer.

• .. the Apache servers Apache 1.3.x, and Apache 2.x.

• .. the Netscape/iPlanet servers.

• .. the OmniHTTPd server.

• .. the Oreilly Website Pro server.

• .. the Sambar server.

• .. the Xitami server.

Building from source

Before getting started, it is worthwhile answering the question: "Why is building on Windows so hard?" Two reasons come to mind:

1. Windows does not (yet) enjoy a large community of developers who are willing to freely share their source. As a direct result, the necessary investment in infrastructure required to support such development hasn't been made. By and large, what is available has been made possible by the porting of necessary utilities from Unix. Don't be surprised if some of this heritage shows through from time to time.

2. Pretty much all of the instructions that follow are of the "set and forget" variety. So sit back and try follow the instructions below as faithfully as you can.

+--c:\work
|  |
|  +--bindlib_w32
|  |  |
|  |  +--arpa
|  |  |
|  |  +--conf
|  |  |
|  |  +--...
|  |
|  +--php-4.x.x
|  |  |
|  |  +--build
|  |  |
|  |  +--...
|  |  |
|  |  +--win32
|  |  |
|  |  +--...
|  |
|  +--win32build
|  |  |
|  |  +--bin
|  |  |
|  |  +--include
|  |  |
|  |  +--lib

Installation of Windows extensions

After installing PHP and a webserver on Windows, you will probably want to install some extensions for added functionality. You can choose which extensions you would like to load when PHP starts by modifying your php.ini. You can also load a module dynamically in your script using dl().

The DLLs for PHP extensions are prefixed with 'php_' in PHP 4 (and 'php3_' in PHP 3). This prevents confusion between PHP extensions and their supporting libraries.

The default location PHP searches for extensions is c:\php4\extensions. To change this setting to reflect your setup of PHP edit your php.ini file:

• You will need to change the extension_dir setting to point to the directory where your extensions lives, or where you have placed your php_*.dll files. Please do not forget the last backslash. For example:

  extension_dir = c:/php/extensions/

• Enable the extension(s) in php.ini you want to use by uncommenting the extension=php_*.dll lines in php.ini. This is done by deleting the leading ; form the extension you want to load.

  Príklad 3-3. Enable Bzip2 extension for PHP-Windows // change the following line from ... ;extension=php_bz2.dll // ... to extension=php_bz2.dll

• Some of the extensions need extra DLLs to work. Couple of them can be found in the distribution package, in the c:\php\dlls\ folder but some, for example Oracle (php_oci8.dll) require DLLs which are not bundled with the distribution package. Copy the bundled DLLs from c:\php\dlls folder to your Windows PATH, safe places are:

  c:\windows\system for Windows 9x/Me

  c:\winnt\system32 for Windows NT/2000

  c:\windows\system32 for Windows XP

  If you have them already installed on your system, overwrite them only if something doesn't work correctly (Before overwriting them, it is a good idea to make a backup of them, or move them to another folder - just in case something goes wrong).

The following table describes some of the extensions available and required additional dlls.

Testing

If you have built PHP as a CGI program, you may test your build by typing make test. It is always a good idea to test your build. This way you may catch a problem with PHP on your platform early instead of having to struggle with it later.

Benchmarking

If you have built PHP 3 as a CGI program, you may benchmark your build by typing make bench. Note that if safe mode is on by default, the benchmark may not be able to finish if it takes longer then the 30 seconds allowed. This is because the set_time_limit() can not be used in safe mode. Use the max_execution_time configuration setting to control this time for your own scripts. make bench ignores the configuration file.

Using Variables

Some server supplied environment variables are not defined in the current CGI/1.1 specification. Only the following variables are defined there; everything else should be treated as 'vendor extensions': AUTH_TYPE, CONTENT_LENGTH, CONTENT_TYPE, GATEWAY_INTERFACE, PATH_INFO, PATH_TRANSLATED, QUERY_STRING, REMOTE_ADDR, REMOTE_HOST, REMOTE_IDENT, REMOTE_USER, REQUEST_METHOD, SCRIPT_NAME, SERVER_NAME, SERVER_PORT, SERVER_PROTOCOL and SERVER_SOFTWARE

Details of installing PHP with Apache on Unix

You can select arguments to add to the configure on line 10 below from the Complete list of configure options. The version numbers have been omitted here, to ensure the instructions are not incorrect. You will need to replace the 'xxx' here with the correct values from your files.

1.  gunzip apache_xxx.tar.gz
2.  tar -xvf apache_xxx.tar
3.  gunzip php-xxx.tar.gz
4.  tar -xvf php-xxx.tar
5.  cd apache_xxx
6.  ./configure --prefix=/www --enable-module=so
7.  make
8.  make install
9.  cd ../php-xxx

10. Now, configure your PHP.  This is where you customize your PHP
    with various options, like which extensions will be enabled.  Do a
    ./configure --help for a list of available options.  In our example
    we'll do a simple configure with Apache 1 and MySQL support.  Your
    path to apxs may differ from our example.

      ./configure --with-mysql --with-apxs=/www/bin/apxs

11. make
12. make install

    If you decide to change your configure options after installation,
    you only need to repeat the last three steps. You only need to 
    restart apache for the new module to take effect. A recompile of
    Apache is not needed.
  
    Note that unless told otherwise, 'make install' will also install PEAR,
    various PHP tools such as phpize, install the PHP CLI, and more.

13. Setup your php.ini file:

      cp php.ini-dist /usr/local/lib/php.ini

    You may edit your .ini file to set PHP options.  If you prefer your
    php.ini in another location, use --with-config-file-path=/some/path in
    step 10. 
    
    If you instead choose php.ini-recommended, be certain to read the list
    of changes within, as they affect how PHP behaves.

14. Edit your httpd.conf to load the PHP module.  The path on the right hand
    side of the LoadModule statement must point to the path of the PHP
    module on your system.  The make install from above may have already
    added this for you, but be sure to check.
        
    For PHP 4:
            
      LoadModule php4_module libexec/libphp4.so

    For PHP 5:
                      
      LoadModule php5_module libexec/libphp5.so
      
15. And in the AddModule section of httpd.conf, somewhere under the
    ClearModuleList, add this:
    
    For PHP 4:
    
      AddModule mod_php4.c
      
    For PHP 5:
    
      AddModule mod_php5.c

16. Tell Apache to parse certain extensions as PHP.  For example,
    let's have Apache parse the .php extension as PHP.  You could
    have any extension(s) parse as PHP by simply adding more, with
    each separated by a space.  We'll add .phtml to demonstrate.

      AddType application/x-httpd-php .php .phtml

    It's also common to setup the .phps extension to show highlighted PHP
    source, this can be done with:
    
      AddType application/x-httpd-php-source .phps

17. Use your normal procedure for starting the Apache server. (You must
    stop and restart the server, not just cause the server to reload by
    using a HUP or USR1 signal.)

Depending on your Apache install and Unix variant, there are many possible ways to stop and restart the server. Below are some typical lines used in restarting the server, for different apache/unix installations. You should replace /path/to/ with the path to these applications on your systems.

Príklad 3-5. Example commands for restarting Apache 1. Several Linux and SysV variants: /etc/rc.d/init.d/httpd restart 2. Using apachectl scripts: /path/to/apachectl stop /path/to/apachectl start 3. httpdctl and httpsdctl (Using OpenSSL), similar to apachectl: /path/to/httpsdctl stop /path/to/httpsdctl start 4. Using mod_ssl, or another SSL server, you may want to manually stop and start: /path/to/apachectl stop /path/to/apachectl startssl

The locations of the apachectl and http(s)dctl binaries often vary. If your system has locate or whereis or which commands, these can assist you in finding your server control programs.

Different examples of compiling PHP for apache are as follows:

./configure --with-apxs --with-pgsql

This will create a libphp4.so shared library that is loaded into Apache using a LoadModule line in Apache's httpd.conf file. The PostgreSQL support is embedded into this libphp4.so library.

./configure --with-apxs --with-pgsql=shared

This will create a libphp4.so shared library for Apache, but it will also create a pgsql.so shared library that is loaded into PHP either by using the extension directive in php.ini file or by loading it explicitly in a script using the dl() function.

./configure --with-apache=/path/to/apache_source --with-pgsql

This will create a libmodphp4.a library, a mod_php4.c and some accompanying files and copy this into the src/modules/php4 directory in the Apache source tree. Then you compile Apache using --activate-module=src/modules/php4/libphp4.a and the Apache build system will create libphp4.a and link it statically into the httpd binary. The PostgreSQL support is included directly into this httpd binary, so the final result here is a single httpd binary that includes all of Apache and all of PHP.

./configure --with-apache=/path/to/apache_source --with-pgsql=shared

Same as before, except instead of including PostgreSQL support directly into the final httpd you will get a pgsql.so shared library that you can load into PHP from either the php.ini file or directly using dl().

When choosing to build PHP in different ways, you should consider the advantages and drawbacks of each method. Building as a shared object will mean that you can compile apache separately, and don't have to recompile everything as you add to, or change, PHP. Building PHP into apache (static method) means that PHP will load and run faster. For more information, see the Apache webpage on DSO support.

Installing PHP on Windows with Apache 1.3.x

There are two ways to set up PHP to work with Apache 1.3.x on Windows. One is to use the CGI binary (php.exe), the other is to use the Apache module DLL. In either case you need to stop the Apache server, and edit your httpd.conf to configure Apache to work with PHP.

It is worth noting here that now the SAPI module has been made more stable under Windows, we recommend it's use above the CGI binary, since it is more transparent and secure.

Although there can be a few variations of configuring PHP under Apache, these are simple enough to be used by the newcomer. Please consult the Apache Docs for further configuration directives.

If you unziped the PHP package to c:\php\ as described in the Manual Installation Steps section, you need to insert these lines to your Apache configuration file to set up the CGI binary:

• ScriptAlias /php/ "c:/php/"

• AddType application/x-httpd-php .php .phtml

• Action application/x-httpd-php "/php/php.exe"

If you would like to use PHP as a module in Apache, be sure to copy php4ts.dll to the windows/system (for Windows 9x/Me), winnt/system32 (for Windows NT/2000) or windows/system32 (for Windows XP) directory, overwriting any older file. Then you should add the following lines to your Apache httpd.conf file:

• Open httpd.conf with your favorite editor and locate the LoadModule directive and add the following line at the end of the list for PHP 4: LoadModule php4_module "c:/php/sapi/php4apache.dll" or the following for PHP 5: LoadModule php5_module "c:/php/sapi/php5apache.dll"

• You may find after using the Windows installer for Apache that you need to define the AddModule directive for mod_php4.c. This is especially important if the ClearModuleList directive is defined, which you will find by scrolling down a few lines. You will see a list of AddModule entries, add the following line at the end of the list: AddModule mod_php4.c For PHP 5, instead use AddModule mod_php5.c

• Search for a phrase similar to # AddType allows you to tweak mime.types. You will see some AddType entries, add the following line at the end of the list: AddType application/x-httpd-php .php. You can choose any extension you want to parse through PHP here. .php is simply the one we suggest. You can even include .html, and .php3 can be added for backwards compatibility.

After changing the configuration file, remember to restart the server, for example, NET STOP APACHE followed by NET START APACHE, if you run Apache as a Windows Service, or use your regular shortcuts.

There are two ways you can use the source code highlighting feature, however their ability to work depends on your installation. If you have configured Apache to use PHP as an SAPI module, then by adding the following line to your httpd.conf (at the same place you inserted AddType application/x-httpd-php .php, see above) you can use this feature: AddType application/x-httpd-php-source .phps.

If you chose to configure Apache to use PHP as a CGI binary, you will need to use the show_source() function. To do this simply create a PHP script file and add this code: <?php show_source ("original_php_script.php"); ?>. Substitute original_php_script.php with the name of the file you wish to show the source of.

PHP and Apache 2.0 compatibility notes

The following versions of PHP are known to work with the most recent version of Apache 2.0:

• PHP 4.3.0 or later available at http://www.php.net/downloads.php.
• the latest stable development version. Get the source code http://snaps.php.net/php4-latest.tar.gz or download binaries for Windows http://snaps.php.net/win32/php4-win32-latest.zip.
• a prerelease version downloadable from http://qa.php.net/.
• you have always the option to obtain PHP through anonymous CVS.

PHP and Apache 2 on Linux

Download the most recent version of Apache 2.0 and a fitting PHP version from the above mentioned places. This quick guide covers only the basics to get started with Apache 2.0 and PHP. For more information read the Apache Documentation. The version numbers have been omitted here, to ensure the instructions are not incorrect. You will need to replace the 'NN' here with the correct values from your files.

1.  gzip -d httpd-2_0_NN.tar.gz
2.  tar xvf httpd-2_0_NN.tar
3.  gunzip php-NN.tar.gz
4.  tar -xvf php-NN.tar
5.  cd httpd-2_0_NN
6.  ./configure --enable-so
7.  make
8.  make install

    Now you have Apache 2.0.NN available under /usr/local/apache2,
    configured with loadable module support and the standard MPM prefork.
    To test the installation use your normal procedure for starting
    the Apache server, e.g.:
    /usr/local/apache2/bin/apachectl start
    and stop the server to go on with the configuration for PHP:
    /usr/local/apache2/bin/apachectl stop.

9.  cd ../php-NN

10. Now, configure your PHP.  This is where you customize your PHP
    with various options, like which extensions will be enabled.  Do a
    ./configure --help for a list of available options.  In our example
    we'll do a simple configure with Apache 2 and MySQL support.  Your
    path to apxs may differ, in fact, the binary may even be named apxs2 on
    your system. 
    
      ./configure --with-apxs2=/usr/local/apache2/bin/apxs --with-mysql

11. make
12. make install

    If you decide to change your configure options after installation,
    you only need to repeat the last three steps. You only need to
    restart apache for the new module to take effect. A recompile of
    Apache is not needed.
                
    Note that unless told otherwise, 'make install' will also install PEAR,
    various PHP tools such as phpize, install the PHP CLI, and more.
    
13. Setup your php.ini 
    
    cp php.ini-dist /usr/local/lib/php.ini
          
    You may edit your .ini file to set PHP options.  If you prefer having
    php.ini in another location, use --with-config-file-path=/some/path in
    step 10.
    
    If you instead choose php.ini-recommended, be certain to read the list
    of changes within, as they affect how PHP behaves.

14. Edit your httpd.conf to load the PHP module.  The path on the right hand
    side of the LoadModule statement must point to the path of the PHP
    module on your system.  The make install from above may have already
    added this for you, but be sure to check.

    For PHP 4:
  
      LoadModule php4_module libexec/libphp4.so
      
    For PHP 5:
    
      LoadModule php5_module libexec/libphp5.so
 
15. Tell Apache to parse certain extensions as PHP.  For example,
    let's have Apache parse the .php extension as PHP.  You could
    have any extension(s) parse as PHP by simply adding more, with
    each separated by a space.  We'll add .phtml to demonstrate.
            
      AddType application/x-httpd-php .php .phtml
                  
    It's also common to setup the .phps extension to show highlighted PHP
    source, this can be done with:
    
      AddType application/x-httpd-php-source .phps
 
16. Use your normal procedure for starting the Apache server, e.g.:
   
      /usr/local/apache2/bin/apachectl start

Following the steps above you will have a running Apache 2.0 with support for PHP as SAPI module. Of course there are many more configuration options available for both, Apache and PHP. For more information use ./configure --help in the corresponding source tree. In case you wish to build a multithreaded version of Apache 2.0 you must overwrite the standard MPM-Module prefork either with worker or perchild. To do so append to your configure line in step 6 above either the option --with-mpm=worker or --with-mpm=perchild. Take care about the consequences and understand what you are doing. For more information read the Apache documentation about the MPM-Modules.

PHP and Apache 2.0 on Windows

Consider to read the Windows specific notes for Apache 2.0.

Download the most recent version of Apache 2.0 and a fitting PHP version from the above mentioned places. Follow the Manual Installation Steps and come back to go on with the integration of PHP and Apache.

There are two ways to set up PHP to work with Apache 2.0 on Windows. One is to use the CGI binary the other is to use the Apache module DLL. In either case you need to stop the Apache server, and edit your httpd.conf to configure Apache to work with PHP.

You need to insert these three lines to your Apache httpd.conf configuration file to set up the CGI binary:

Príklad 3-7. PHP and Apache 2.0 as CGI ScriptAlias /php/ "c:/php/" AddType application/x-httpd-php .php Action application/x-httpd-php "/php/php.exe"

If you would like to use PHP as a module in Apache 2.0, be sure to move php4ts.dll for PHP 4, or php5ts.dll for PHP 5, to winnt/system32 (for Windows NT/2000) or windows/system32 (for Windows XP), overwriting any older file. You need to insert these two lines to your Apache httpd.conf configuration file to set up the PHP-Module for Apache 2.0:

Príklad 3-8. PHP and Apache 2.0 as Module ; For PHP 4 do something like this: LoadModule php4_module "c:/php/sapi/php4apache2.dll" AddType application/x-httpd-php .php ; For PHP 5 do something like this: LoadModule php5_module "c:/php/sapi/php5apache2.dll" AddType application/x-httpd-php .php

Windows and PWS/IIS 3

The recommended method for configuring these servers is to use the REG file included with the distribution (pws-php4cgi.reg). You may want to edit this file and make sure the extensions and PHP install directories match your configuration. Or you can follow the steps below to do it manually.

• Run Regedit.

• Navigate to: HKEY_LOCAL_MACHINE /System /CurrentControlSet /Services /W3Svc /Parameters /ScriptMap.

• On the edit menu select: New->String Value.

• Type in the extension you wish to use for your php scripts. For example .php

• Double click on the new string value and enter the path to php.exe in the value data field. ex: c:\php\php.exe.

• Repeat these steps for each extension you wish to associate with PHP scripts.

The following steps do not affect the web server installation and only apply if you want your PHP scripts to be executed when they are run from the command line (ex. run c:\myscripts\test.php) or by double clicking on them in a directory viewer window. You may wish to skip these steps as you might prefer the PHP files to load into a text editor when you double click on them.

• Navigate to: HKEY_CLASSES_ROOT

• On the edit menu select: New->Key.

• Name the key to the extension you setup in the previous section. ex: .php

• Highlight the new key and in the right side pane, double click the "default value" and enter phpfile.

• Repeat the last step for each extension you set up in the previous section.

• Now create another New->Key under HKEY_CLASSES_ROOT and name it phpfile.

• Highlight the new key phpfile and in the right side pane, double click the "default value" and enter PHP Script.

• Right click on the phpfile key and select New->Key, name it Shell.

• Right click on the Shell key and select New->Key, name it open.

• Right click on the open key and select New->Key, name it command.

• Highlight the new key command and in the right side pane, double click the "default value" and enter the path to php.exe. ex: c:\php\php.exe -q %1. (don't forget the %1).

• Exit Regedit.

• If using PWS on Windows, reboot to reload the registry.

PWS and IIS 3 users now have a fully operational system. IIS 3 users can use a nifty tool from Steven Genusa to configure their script maps.

Windows and PWS 4 or newer

When installing PHP on Windows with PWS 4 or newer version, you have two options. One to set up the PHP CGI binary, the other is to use the ISAPI module DLL.

If you choose the CGI binary, do the following:

• Edit the enclosed pws-php4cgi.reg file (look into the SAPI dir) to reflect the location of your php.exe. Backslashes should be escaped, for example: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w3svc\parameters\Script Map] ".php"="c:\\php\\php.exe" Now merge this registery file into your system; you may do this by double-clicking it.

• In the PWS Manager, right click on a given directory you want to add PHP support to, and select Properties. Check the 'Execute' checkbox, and confirm.

If you choose the ISAPI module, do the following:

• Edit the enclosed pws-php4isapi.reg file (look into the SAPI dir) to reflect the location of your php4isapi.dll. Backslashes should be escaped, for example: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w3svc\parameters\Script Map] ".php"="c:\\php\\sapi\\php4isapi.dll" Now merge this registery file into your system; you may do this by double-clicking it.

• In the PWS Manager, right click on a given directory you want to add PHP support to, and select Properties. Check the 'Execute' checkbox, and confirm.

Windows NT/2000/XP and IIS 4 or newer

To install PHP on an NT/2000/XP Server running IIS 4 or newer, follow these instructions. You have two options to set up PHP, using the CGI binary (php.exe) or with the ISAPI module.

In either case, you need to start the Microsoft Management Console (may appear as 'Internet Services Manager', either in your Windows NT 4.0 Option Pack branch or the Control Panel=>Administrative Tools under Windows 2000/XP). Then right click on your Web server node (this will most probably appear as 'Default Web Server'), and select 'Properties'.

If you want to use the CGI binary, do the following:

• Under 'Home Directory', 'Virtual Directory', or 'Directory', click on the 'Configuration' button, and then enter the App Mappings tab.

• Click Add, and in the Executable box, type: c:\php\php.exe (assuming that you have unziped PHP in c:\php\).

• In the Extension box, type the file name extension you want associated with PHP scripts. Leave 'Method exclusions' blank, and check the Script engine checkbox. You may also like to check the 'check that file exists' box - for a small performance penalty, IIS (or PWS) will check that the script file exists and sort out authentication before firing up php. This means that you will get sensible 404 style error messages instead of cgi errors complaining that PHP did not output any data.

  You must start over from the previous step for each extension you want associated with PHP scripts. .php and .phtml are common, although .php3 may be required for legacy applications.

• Set up the appropriate security. (This is done in Internet Service Manager), and if your NT Server uses NTFS file system, add execute rights for I_USR_ to the directory that contains php.exe.

To use the ISAPI module, do the following:

• If you don't want to perform HTTP Authentication using PHP, you can (and should) skip this step. Under ISAPI Filters, add a new ISAPI filter. Use PHP as the filter name, and supply a path to the php4isapi.dll.

• Under 'Home Directory', click on the 'Configuration' button. Add a new entry to the Application Mappings. Use the path to the php4isapi.dll as the Executable, supply .php as the extension, leave Method exclusions blank, and check the Script engine checkbox.

• Stop IIS completely (NET STOP iisadmin)

• Start IIS again (NET START w3svc)

Installing PHP with NES/iPlanet/SunONE Webserver on Sun Solaris

To build PHP with NES/iPlanet/SunONE webservers, enter the proper install directory for the --with-nsapi=[DIR] option. The default directory is usually /opt/netscape/suitespot/. Please also read /php-xxx-version/sapi/nsapi/nsapi-readme.txt.

1. Install the following packages from http://www.sunfreeware.com/ or another download site:

   autoconf-2.13

   automake-1.4

   bison-1_25-sol26-sparc-local

   flex-2_5_4a-sol26-sparc-local

   gcc-2_95_2-sol26-sparc-local

   gzip-1.2.4-sol26-sparc-local

   m4-1_4-sol26-sparc-local

   make-3_76_1-sol26-sparc-local

   mysql-3.23.24-beta (if you want mysql support)

   perl-5_005_03-sol26-sparc-local

   tar-1.13 (GNU tar)

2. Make sure your path includes the proper directories PATH=.:/usr/local/bin:/usr/sbin:/usr/bin:/usr/ccs/bin and make it available to your system export PATH.

3. gunzip php-x.x.x.tar.gz (if you have a .gz dist, otherwise go to 4).

4. tar xvf php-x.x.x.tar

5. Change to your extracted PHP directory: cd ../php-x.x.x

6. For the following step, make sure /opt/netscape/suitespot/ is where your netscape server is installed. Otherwise, change to the correct path and run:

   ./configure --with-mysql=/usr/local/mysql \ --with-nsapi=/opt/netscape/suitespot/ \ --enable-libgcc

7. Run make followed by make install.

After performing the base install and reading the appropriate readme file, you may need to perform some additional configuration steps.

Installing PHP with NES/iPlanet/SunONE on Windows

To Install PHP as CGI (for Netscape Enterprise Server, iPlanet, SunONE, perhaps Fastrack), do the following:

• Copy php4ts.dll to your systemroot (the directory where you installed Windows)

• Make a file association from the command line. Type the following two lines:

  assoc .php=PHPScript ftype PHPScript=c:\php\php.exe %1 %*

• In the Netscape Enterprise Administration Server create a dummy shellcgi directory and remove it just after (this step creates 5 important lines in obj.conf and allow the web server to handle shellcgi scripts).

• In the Netscape Enterprise Administration Server create a new mime type (Category: type, Content-Type: magnus-internal/shellcgi, File Suffix:php).

• Do it for each web server instance you want PHP to run

More details about setting up PHP as a CGI executable can be found here: http://benoit.noss.free.fr/php/install-php.html

To Install PHP as NSAPI (for Netscape Enterprise Server, iPlanet, SunONE, perhaps Fastrack), do the following:

• Copy php4ts.dll to your systemroot (the directory where you installed Windows)

• Make a file association from the command line. Type the following two lines:

  assoc .php=PHPScript ftype PHPScript=c:\php\php.exe %1 %*

• In the Netscape Enterprise Administration Server create a new mime type (Category: type, Content-Type: magnus-internal/x-httpd-php, File Suffix: php).

• Edit magnus.conf (for servers >= 6) or obj.conf (for servers < 6) and add the following: You should place the lines after mime types init.

  Init fn="load-modules" funcs="php4_init,php4_execute,php4_auth_trans" shlib="c:/php/sapi/php4nsapi.dll" Init fn="php4_init" LateInit="yes" errorString="Failed to initialise PHP!" [php_ini="c:/path/to/php.ini"]

  (PHP >= 4.3.3) The php_ini parameter is optional but with it you can place your php.ini in your webserver config directory.

• Configure the default object in obj.conf (for virtual server classes [SunONE 6.0+] in their vserver.obj.conf): In the <Object name="default"> section, place this line necessarily after all 'ObjectType' and before all 'AddLog' lines:

  Service fn="php4_execute" type="magnus-internal/x-httpd-php" [inikey=value inikey=value ...]

  (PHP >= 4.3.3) As additional parameters you can add some special php.ini-values, for example you can set a docroot="/path/to/docroot" specific to the context php4_execute is called. For boolean ini-keys please use 0/1 as value, not "On","Off",... (this will not work correctly), e.g. zlib.output_compression=1 instead of zlib.output_compression="On"

• This is only needed if you want to configure a directory that only consists of PHP scripts (same like a cgi-bin directory):

  <Object name="x-httpd-php"> ObjectType fn="force-type" type="magnus-internal/x-httpd-php" Service fn=php4_execute [inikey=value inikey=value ...] </Object>

  After that you can configure a directory in the Administration server and assign it the style x-httpd-php. All files in it will get executed as PHP. This is nice to hide PHP usage by renaming files to .html.

• Restart your web service and apply changes

• Do it for each web server instance you want PHP to run

CGI environment and recommended modifications in php.ini

Important when writing PHP scripts is the fact that iPlanet/SunONE/Netscape is a multithreaded web server. Because of that all requests are running in the same process space (the space of the webserver itsself) and this space has only one environment. If you want to get CGI variables like PATH_INFO, HTTP_HOST etc. it is not the correct way to try this in the old PHP 3.x way with getenv() or a similar way (register globals to environment, $_ENV). You would only get the environment of the running webserver without any valid CGI variables!

Simply change your scripts to get CGI variables in the correct way for PHP 4.x by using the superglobal $_SERVER. If you have older scripts which use $HTTP_HOST,..., you should turn on register_globals in php.ini and change the variable order to (important: remove "E" from it, because you do not need the environment here):

variables_order = "GPCS" register_globals = On

Special use for error pages or self-made directory listings (PHP >= 4.3.3)

You can use PHP to generate the error pages for "404 Not Found" or similar. Add the following line to the object in obj.conf for every error page you want to overwrite:

Error fn="php4_execute" code=XXX script="/path/to/script.php" [inikey=value inikey=value...]

where XXX is the HTTP error code. Please delete any other Error directives which could interfere with yours. If you want to place a page for all errors that could exist, leave the code parameter out. Your script can get the HTTP status code with $_SERVER['ERROR_TYPE'].

Another possibility is to generate self-made directory listings. Just create a PHP script which displays a directory listing and replace the corresponding default Service line for type="magnus-internal/directory" in obj.conf with the following:

Service fn="php4_execute" type="magnus-internal/directory" script="/path/to/script.php" [inikey=value inikey=value...]

For both error and directory listing pages the original URI and translated URI are in the variables $_SERVER['PATH_INFO'] and $_SERVER['PATH_TRANSLATED'].

Note about nsapi_virtual() and subrequests (PHP >= 4.3.3)

The NSAPI module now supports the nsapi_virtual() function (alias: virtual()) to make subrequests on the webserver and insert the result in the webpage. The problem is, that this function uses some undocumented features from the NSAPI library.

Under Unix this is not a problem, because the module automatically looks for the needed functions and uses them if available. If not, nsapi_virtual() is disabled.

Under Windows limitations in the DLL handling need the use of a automatic detection of the most recent ns-httpdXX.dll file. This is tested for servers till version 6.1. If a newer version of the SunONE server is used, the detection fails and nsapi_virtual() is disabled.

If this is the case, try the following: Add the following parameter to php4_init in magnus.conf/obj.conf:

Init fn=php4_init ... server_lib="ns-httpdXX.dll"

where XX is the correct DLL version number. To get it, look in the server-root for the correct DLL name. The DLL with the biggest filesize is the right one.

You can check the status by using the phpinfo() function.

OmniHTTPd 2.0b1 and up for Windows

You need to complete the following steps to make PHP work with OmniHTTPd. This is a CGI executable setup. SAPI is supported by OmniHTTPd, but some tests have shown that it is not so stable to use PHP as an ISAPI module.

1. Install OmniHTTPd server.

2. Right click on the blue OmniHTTPd icon in the system tray and select Properties

3. Click on Web Server Global Settings

4. On the 'External' tab, enter: virtual = .php | actual = c:\path-to-php-dir\php.exe, and use the Add button.

5. On the Mime tab, enter: virtual = wwwserver/stdcgi | actual = .php, and use the Add button.

6. Click OK

Repeat steps 2 - 6 for each extension you want to associate with PHP.

Oreilly Website Pro 2.5 and up for Windows

This list describes how to set up the PHP CGI binary or the ISAPI module to work with Oreilly Website Pro on Windows.

• Edit the Server Properties and select the tab "Mapping".

• From the List select "Associations" and enter the desired extension (.php) and the path to the CGI exe (ex. c:\php\php.exe) or the ISAPI DLL file (ex. c:\php\sapi\php4isapi.dll).

• Select "Content Types" add the same extension (.php) and enter the content type. If you choose the CGI executable file, enter 'wwwserver/shellcgi', if you choose the ISAPI module, enter 'wwwserver/isapi' (both without quotes).

Sambar Windows

This list describes how to set up the ISAPI module to work with the Sambar server on Windows.

• Find the file called mappings.ini (in the config directory) in the Sambar install directory.

• Open mappings.ini and add the following line under [ISAPI]:

  *.php = c:\php\php4isapi.dll

  (This line assumes that PHP was installed in c:\php.)

• Now restart the Sambar server for the changes to take effect.

Xitami for Windows

This list describes how to set up the PHP CGI binary to work with Xitami on Windows.

• Make sure the webserver is running, and point your browser to xitamis admin console (usually http://127.0.0.1/admin), and click on Configuration.

• Navigate to the Filters, and put the extension which PHP should parse (i.e. .php) into the field File extensions (.xxx).

• In Filter command or script put the path and name of your PHP executable i.e. c:\php\php.exe.

• Press the 'Save' icon.

• Restart the server to reflect changes.

Read the FAQ

Some problems are more common than others. The most common ones are listed in the PHP FAQ, part of this manual.

Other problems

If you are still stuck, someone on the PHP installation mailing list may be able to help you. You should check out the archive first, in case someone already answered someone else who had the same problem as you. The archives are available from the support page on http://www.php.net/support.php. To subscribe to the PHP installation mailing list, send an empty mail to php-install-subscribe@lists.php.net. The mailing list address is php-install@lists.php.net.

If you want to get help on the mailing list, please try to be precise and give the necessary details about your environment (which operating system, what PHP version, what web server, if you are running PHP as CGI or a server module, safe mode, etc...), and preferably enough code to make others able to reproduce and test your problem.

Bug reports

If you think you have found a bug in PHP, please report it. The PHP developers probably don't know about it, and unless you report it, chances are it won't be fixed. You can report bugs using the bug-tracking system at http://bugs.php.net/. Please do not send bug reports in mailing list or personal letters. The bug system is also suitable to submit feature requests.

Read the How to report a bug document before submitting any bug reports!

Configure Options in PHP 4

Running PHP as Apache module

When using PHP as an Apache module, you can also change the configuration settings using directives in Apache configuration files (e.g. httpd.conf) and .htaccess files (You will need "AllowOverride Options" or "AllowOverride All" privileges)

With PHP 4.0, there are several Apache directives that allow you to change the PHP configuration from within the Apache configuration files. For a listing of which directives are PHP_INI_ALL, PHP_INI_PERDIR, or PHP_INI_SYSTEM, have a look at the table found within the ini_set() documentation.

Príklad 4-2. Apache configuration example <IfModule mod_php4.c> php_value include_path ".:/usr/local/lib/php" php_admin_flag safe_mode on </IfModule> <IfModule mod_php3.c> php3_include_path ".:/usr/local/lib/php" php3_safe_mode on </IfModule>

Changing PHP configuration via the Windows registry

When running PHP on Windows, the configuration values can be modified on per-directory basis using the Windows registry. The configuration values are stored in the registry key HKLM\SOFTWARE\PHP\Per Directory Values, in the sub-keys corresponding to the path names. For example, configuration values for the directory c:\inetpub\wwwroot would be stored in the key HKLM\SOFTWARE\PHP\Per Directory Values\c\inetpub\wwwroot. The settings for the directory would be active for any script running from this directory or any subdirectory of it. The values under the key should have the name of PHP configuration directive and the string value. PHP constants in the values would not be parsed.

Other interfaces to PHP

Regardless of the interface to PHP you can change certain values at runtime of your scripts through ini_set(). The following table provides an overview at which level a directive can be set/changed.

You can view the settings of the configuration values in the output of phpinfo(). You can also access the values of individual configuration directives using ini_get() or get_cfg_var().

Httpd Options

Language Options

Tu je short vysvetlenie of the configuration directives.

Resource Limits

Tu je short vysvetlenie of the configuration directives.

See also: max_execution_time.

Data Handling

Tu je short vysvetlenie of the configuration directives.

See also: magic_quotes_gpc, magic-quotes-runtime, and magic_quotes_sybase.

Paths and Directories

Tu je short vysvetlenie of the configuration directives.

File Uploads

Tu je short vysvetlenie of the configuration directives.

General SQL

Tu je short vysvetlenie of the configuration directives.

Debugger Configuration Directives

Syntax

To specify a boolean literal, use either the keyword TRUE or FALSE. Both are case-insensitive.

<?php
$foo = True; // assign the value TRUE to $foo
?>

Usually you use some kind of operator which returns a boolean value, and then pass it on to a control structure.

<?php
// == is an operator which test
// equality and returns a boolean
if ($action == "show_version") {
    echo "The version is 1.23";
}

// this is not necessary...
if ($show_separators == TRUE) {
    echo "<hr>\n";
}

// ...because you can simply type
if ($show_separators) {
    echo "<hr>\n";
}
?>

Converting to boolean

To explicitly convert a value to boolean, use either the (bool) or the (boolean) cast. However, in most cases you do not need to use the cast, since a value will be automatically converted if an operator, function or control structure requires a boolean argument.

See also Type Juggling.

When converting to boolean, the following values are considered FALSE:

• the boolean FALSE itself

• the integer 0 (zero)

• the float 0.0 (zero)

• the empty string, and the string "0"

• an array with zero elements

• an object with zero member variables

• the special type NULL (including unset variables)

<?php
echo gettype((bool) "");        // bool(false)
echo gettype((bool) 1);         // bool(true)
echo gettype((bool) -2);        // bool(true)
echo gettype((bool) "foo");     // bool(true)
echo gettype((bool) 2.3e5);     // bool(true)
echo gettype((bool) array(12)); // bool(true)
echo gettype((bool) array());   // bool(false)
?>

Syntax

Integers can be specified in decimal (10-based), hexadecimal (16-based) or octal (8-based) notation, optionally preceded by a sign (- or +).

If you use the octal notation, you must precede the number with a 0 (zero), to use hexadecimal notation precede the number with 0x.

Príklad 6-1. Integer literals <?php $a = 1234; # decimal number $a = -123; # a negative number $a = 0123; # octal number (equivalent to 83 decimal) $a = 0x1A; # hexadecimal number (equivalent to 26 decimal) ?>

Formally the possible structure for integer literals is:

decimal     : [1-9][0-9]*
            | 0

hexadecimal : 0[xX][0-9a-fA-F]+

octal       : 0[0-7]+

integer     : [+-]?decimal
            | [+-]?hexadecimal
            | [+-]?octal

Integer overflow

If you specify a number beyond the bounds of the integer type, it will be interpreted as a float instead. Also, if you perform an operation that results in a number beyond the bounds of the integer type, a float will be returned instead.

<?php
$large_number =  2147483647;
var_dump($large_number);
// output: int(2147483647)

$large_number =  2147483648;
var_dump($large_number);
// output: float(2147483648)

// this goes also for hexadecimal specified integers:
var_dump( 0x80000000 );
// output: float(2147483648)

$million = 1000000;
$large_number =  50000 * $million;
var_dump($large_number);
// output: float(50000000000)
?>

There is no integer division operator in PHP. 1/2 yields the float 0.5. You can cast the value to an integer to always round it downwards, or you can use the round() function.

<?php
var_dump(25/7);         // float(3.5714285714286) 
var_dump((int) (25/7)); // int(3)
var_dump(round(25/7));  // float(4) 
?>

Converting to integer

To explicitly convert a value to integer, use either the (int) or the (integer) cast. However, in most cases you do not need to use the cast, since a value will be automatically converted if an operator, function or control structure requires an integer argument. You can also convert a value to integer with the function intval().

See also type-juggling.

<?php
echo (int) ( (0.1+0.7) * 10 ); // echoes 7!
?>

Converting to float

For information on when and how strings are converted to floats, see the section titled String conversion to numbers. For values of other types, the conversion is the same as if the value would have been converted to integer and then to float. See the Converting to integer section for more information.

Syntax

A string literal can be specified in three different ways.

• single quoted

• double quoted

• heredoc syntax

<?php
echo 'this is a simple string';

echo 'You can also have embedded newlines in 
strings this way as it is
okay to do';

// Outputs: Arnold once said: "I'll be back"
echo 'Arnold once said: "I\'ll be back"';

// Outputs: You deleted C:\*.*?
echo 'You deleted C:\\*.*?';

// Outputs: You deleted C:\*.*?
echo 'You deleted C:\*.*?';

// Outputs: This will not expand: \n a newline
echo 'This will not expand: \n a newline';

// Outputs: Variables do not $expand $either
echo 'Variables do not $expand $either';
?>

<?php
$beer = 'Heineken';
echo "$beer's taste is great"; // works, "'" is an invalid character for varnames
echo "He drank some $beers";   // won't work, 's' is a valid character for varnames
echo "He drank some ${beer}s"; // works
echo "He drank some {$beer}s"; // works
?>

<?php
// These examples are specific to using arrays inside of strings.
// When outside of a string, always quote your array string keys 
// and do not use {braces} when outside of strings either.

// Let's show all errors
error_reporting(E_ALL);

$fruits = array('strawberry' => 'red', 'banana' => 'yellow');

// Works but note that this works differently outside string-quotes
echo "A banana is $fruits[banana].";

// Works
echo "A banana is {$fruits['banana']}.";

// Works but PHP looks for a constant named banana first
// as described below.
echo "A banana is {$fruits[banana]}.";

// Won't work, use braces.  This results in a parse error.
echo "A banana is $fruits['banana'].";

// Works
echo "A banana is " . $fruits['banana'] . ".";

// Works
echo "This square is $square->width meters broad.";

// Won't work. For a solution, see the complex syntax.
echo "This square is $square->width00 centimeters broad.";
?>

<?php
// Let's show all errors
error_reporting(E_ALL);

$great = 'fantastic';

// Won't work, outputs: This is { fantastic}
echo "This is { $great}";

// Works, outputs: This is fantastic
echo "This is {$great}";
echo "This is ${great}";

// Works
echo "This square is {$square->width}00 centimeters broad."; 

// Works
echo "This works: {$arr[4][3]}";

// This is wrong for the same reason as $foo[bar] is wrong 
// outside a string.  In other words, it will still work but
// because PHP first looks for a constant named foo, it will
// throw an error of level E_NOTICE (undefined constant).
echo "This is wrong: {$arr[foo][3]}"; 

// Works.  When using multi-dimensional arrays, always use
// braces around arrays when inside of strings
echo "This works: {$arr['foo'][3]}";

// Works.
echo "This works: " . $arr['foo'][3];

echo "You can even write {$obj->values[3]->name}";

echo "This is the value of the var named $name: {${$name}}";
?>

Useful functions and operators

Strings may be concatenated using the '.' (dot) operator. Note that the '+' (addition) operator will not work for this. Please see String operators for more information.

There are a lot of useful functions for string modification.

See the string functions section for general functions, the regular expression functions for advanced find&replacing (in two tastes: Perl and POSIX extended).

There are also functions for URL-strings, and functions to encrypt/decrypt strings (mcrypt and mhash).

Finally, if you still didn't find what you're looking for, see also the character type functions.

Converting to string

You can convert a value to a string using the (string) cast, or the strval() function. String conversion is automatically done in the scope of an expression for you where a string is needed. This happens when you use the echo() or print() functions, or when you compare a variable value to a string. Reading the manual sections on Types and Type Juggling will make the following clearer. See also settype().

A boolean TRUE value is converted to the string "1", the FALSE value is represented as "" (empty string). This way you can convert back and forth between boolean and string values.

An integer or a floating point number (float) is converted to a string representing the number with its digits (including the exponent part for floating point numbers).

Arrays are always converted to the string "Array", so you cannot dump out the contents of an array with echo() or print() to see what is inside them. To view one element, you'd do something like echo $arr['foo']. See below for tips on dumping/viewing the entire contents.

Objects are always converted to the string "Object". If you would like to print out the member variable values of an object for debugging reasons, read the paragraphs below. If you would like to find out the class name of which an object is an instance of, use get_class().

Resources are always converted to strings with the structure "Resource id #1" where 1 is the unique number of the resource assigned by PHP during runtime. If you would like to get the type of the resource, use get_resource_type().

NULL is always converted to an empty string.

As you can see above, printing out the arrays, objects or resources does not provide you any useful information about the values themselfs. Look at the functions print_r() and var_dump() for better ways to print out values for debugging.

You can also convert PHP values to strings to store them permanently. This method is called serialization, and can be done with the function serialize(). You can also serialize PHP values to XML structures, if you have WDDX support in your PHP setup.

String conversion to numbers

When a string is evaluated as a numeric value, the resulting value and type are determined as follows.

The string will evaluate as a float if it contains any of the characters '.', 'e', or 'E'. Otherwise, it will evaluate as an integer.

The value is given by the initial portion of the string. If the string starts with valid numeric data, this will be the value used. Otherwise, the value will be 0 (zero). Valid numeric data is an optional sign, followed by one or more digits (optionally containing a decimal point), followed by an optional exponent. The exponent is an 'e' or 'E' followed by one or more digits.

<?php
$foo = 1 + "10.5";                // $foo is float (11.5)
$foo = 1 + "-1.3e3";              // $foo is float (-1299)
$foo = 1 + "bob-1.3e3";           // $foo is integer (1)
$foo = 1 + "bob3";                // $foo is integer (1)
$foo = 1 + "10 Small Pigs";       // $foo is integer (11)
$foo = 4 + "10.2 Little Piggies"; // $foo is float (14.2)
$foo = "10.0 pigs " + 1;          // $foo is float (11)
$foo = "10.0 pigs " + 1.0;        // $foo is float (11)     
?>

For more information on this conversion, see the Unix manual page for strtod(3).

If you would like to test any of the examples in this section, you can cut and paste the examples and insert the following line to see for yourself what's going on:

<?php
echo "\$foo==$foo; type is " . gettype ($foo) . "<br />\n";
?>

Do not expect to get the code of one character by converting it to integer (as you would do in C for example). Use the functions ord() and chr() to convert between charcodes and characters.

Syntax

<?php
$arr = array("foo" => "bar", 12 => true);

echo $arr["foo"]; // bar
echo $arr[12];    // 1
?>

<?php
$arr = array("somearray" => array(6 => 5, 13 => 9, "a" => 42));

echo $arr["somearray"][6];    // 5
echo $arr["somearray"][13];   // 9
echo $arr["somearray"]["a"];  // 42
?>

<?php
// This array is the same as ...
array(5 => 43, 32, 56, "b" => 12);

// ...this array
array(5 => 43, 6 => 32, 7 => 56, "b" => 12);
?>

<?php
$arr = array(5 => 1, 12 => 2);

$arr[] = 56;    // This is the same as $arr[13] = 56;
                // at this point of the script

$arr["x"] = 42; // This adds a new element to
                // the array with key "x"
                
unset($arr[5]); // This removes the element from the array

unset($arr);    // This deletes the whole array
?>

Useful functions

There are quite a few useful functions for working with arrays. See the array functions section.

The foreach control structure exists specifically for arrays. It provides an easy way to traverse an array.

Array do's and don'ts

<?php
$foo[bar] = 'enemy';
echo $foo[bar];
// etc
?>

<?php
// Let's show all errors
error_reporting(E_ALL);

$arr = array('fruit' => 'apple', 'veggie' => 'carrot');

// Correct
print $arr['fruit'];  // apple
print $arr['veggie']; // carrot

// Incorrect.  This works but also throws a PHP error of
// level E_NOTICE because of an undefined constant named fruit
// 
// Notice: Use of undefined constant fruit - assumed 'fruit' in...
print $arr[fruit];    // apple

// Let's define a constant to demonstrate what's going on.  We
// will assign value 'veggie' to a constant named fruit.
define('fruit', 'veggie');

// Notice the difference now
print $arr['fruit'];  // apple
print $arr[fruit];    // carrot

// The following is okay as it's inside a string.  Constants are not
// looked for within strings so no E_NOTICE error here
print "Hello $arr[fruit]";      // Hello apple

// With one exception, braces surrounding arrays within strings
// allows constants to be looked for
print "Hello {$arr[fruit]}";    // Hello carrot
print "Hello {$arr['fruit']}";  // Hello apple

// This will not work, results in a parse error such as:
// Parse error: parse error, expecting T_STRING' or T_VARIABLE' or T_NUM_STRING'
// This of course applies to using autoglobals in strings as well
print "Hello $arr['fruit']";
print "Hello $_GET['foo']";

// Concatenation is another option
print "Hello " . $arr['fruit']; // Hello apple
?>

<?php
echo $arr[somefunc($bar)];
?>

<?php
$error_descriptions[E_ERROR]   = "A fatal error has occured";
$error_descriptions[E_WARNING] = "PHP issued a warning";
$error_descriptions[E_NOTICE]  = "This is just an informal notice";
?>

<?php
$error_descriptions[1] = "A fatal error has occured";
$error_descriptions[2] = "PHP issued a warning";
$error_descriptions[8] = "This is just an informal notice";
?>

Converting to array

For any of the types: integer, float, string, boolean and resource, if you convert a value to an array, you get an array with one element (with index 0), which is the scalar value you started with.

If you convert an object to an array, you get the properties (member variables) of that object as the array's elements. The keys are the member variable names.

If you convert a NULL value to an array, you get an empty array.

Comparing

It is possible to compare arrays by array_diff() and by Array operators.

Examples

The array type in PHP is very versatile, so here will be some examples to show you the full power of arrays.

<?php
// this
$a = array( 'color' => 'red',
            'taste' => 'sweet',
            'shape' => 'round',
            'name'  => 'apple',
                       4        // key will be 0
          );

// is completely equivalent with
$a['color'] = 'red';
$a['taste'] = 'sweet';
$a['shape'] = 'round';
$a['name']  = 'apple';
$a[]        = 4;        // key will be 0

$b[] = 'a';
$b[] = 'b';
$b[] = 'c';
// will result in the array array(0 => 'a' , 1 => 'b' , 2 => 'c'),
// or simply array('a', 'b', 'c')
?>

<?php
// Array as (property-)map
$map = array( 'version'    => 4,
              'OS'         => 'Linux',
              'lang'       => 'english',
              'short_tags' => true
            );
            
// strictly numerical keys
$array = array( 7,
                8,
                0,
                156,
                -10
              );
// this is the same as array(0 => 7, 1 => 8, ...)

$switching = array(         10, // key = 0
                    5    =>  6,
                    3    =>  7, 
                    'a'  =>  4,
                            11, // key = 6 (maximum of integer-indices was 5)
                    '8'  =>  2, // key = 8 (integer!)
                    '02' => 77, // key = '02'
                    0    => 12  // the value 10 will be overwritten by 12
                  );
                  
// empty array
$empty = array();         
?>

<?php
$colors = array('red', 'blue', 'green', 'yellow');

foreach ($colors as $color) {
    echo "Do you like $color?\n";
}

?>

Do you like red?
Do you like blue?
Do you like green?
Do you like yellow?

Note that it is currently not possible to change the values of the array directly in such a loop. A workaround is the following:

Príklad 6-6. Collection <?php foreach ($colors as $key => $color) { // won't work: //$color = strtoupper($color); // works: $colors[$key] = strtoupper($color); } print_r($colors); ?> This will output: Array ( [0] => RED [1] => BLUE [2] => GREEN [3] => YELLOW )

This example creates a one-based array.

Príklad 6-7. One-based index <?php $firstquarter = array(1 => 'January', 'February', 'March'); print_r($firstquarter); ?> This will output: Array ( [1] => 'January' [2] => 'February' [3] => 'March' )

<?php
// fill an array with all items from a directory
$handle = opendir('.');
while (false !== ($file = readdir($handle))) {
    $files[] = $file;
}
closedir($handle); 
?>

Arrays are ordered. You can also change the order using various sorting functions. See the array functions section for more information. You can count the number of items in an array using the count() function.

<?php
sort($files);
print_r($files);
?>

Because the value of an array can be anything, it can also be another array. This way you can make recursive and multi-dimensional arrays.

<?php
$fruits = array ( "fruits"  => array ( "a" => "orange",
                                       "b" => "banana",
                                       "c" => "apple"
                                     ),
                  "numbers" => array ( 1,
                                       2,
                                       3,
                                       4,
                                       5,
                                       6
                                     ),
                  "holes"   => array (      "first",
                                       5 => "second",
                                            "third"
                                     )
                );

// Some examples to address values in the array above 
echo $fruits["holes"][5];    // prints "second"
echo $fruits["fruits"]["a"]; // prints "orange"
unset($fruits["holes"][0]);  // remove "first"

// Create a new multi-dimensional array
$juices["apple"]["green"] = "good"; 
?>

You should be aware that array assignment always involves value copying. You need to use the reference operator to copy an array by reference.

<?php
$arr1 = array(2, 3);
$arr2 = $arr1;
$arr2[] = 4; // $arr2 is changed,
             // $arr1 is still array(2, 3)
             
$arr3 = &$arr1;
$arr3[] = 4; // now $arr1 and $arr3 are the same
?>

Object Initialization

To initialize an object, you use the new statement to instantiate the object to a variable.

<?php
class foo
{
    function do_foo()
    {
        echo "Doing foo."; 
    }
}

$bar = new foo;
$bar->do_foo();
?>

For a full discussion, please read the section Classes and Objects.

Converting to object

If an object is converted to an object, it is not modified. If a value of any other type is converted to an object, a new instance of the stdClass built in class is created. If the value was null, the new instance will be empty. For any other value, a member variable named scalar will contain the value.

<?php
$obj = (object) 'ciao';
echo $obj->scalar;  // outputs 'ciao'
?>

Converting to resource

As resource types hold special handlers to opened files, database connections, image canvas areas and the like, you cannot convert any value to a resource.

Freeing resources

Due to the reference-counting system introduced with PHP 4's Zend Engine, it is automatically detected when a resource is no longer referred to (just like Java). When this is the case, all resources that were in use for this resource are made free by the garbage collector. For this reason, it is rarely ever necessary to free the memory manually by using some free_result function.

Syntax

There is only one value of type NULL, and that is the case-insensitive keyword NULL.

<?php
$var = NULL;       
?>

See also is_null() and unset().

mixed

mixed indicates that a parameter may accept multiple (but not necessarily all) types.

gettype() for example will accept all PHP types, while str_replace() will accept strings and arrays.

number

number indicates that a parameter can be either integer or float.

callback

Some functions like call_user_func() or usort() accept user defined callback functions as a parameter. Callback functions can not only be simple functions but also object methods including static class methods.

A PHP function is simply passed by its name as a string. You can pass any builtin or user defined function with the exception of array(), echo(), empty(), eval(), exit(), isset(), list(), print() and unset().

A method of an instantiated object is passed as an array containing an object as the element with index 0 and a method name as the element with index 1.

Static class methods can also be passed without instantiating an object of that class by passing the class name instead of an object as the element with index 0.

Príklad 6-11. Callback function examples <?php // simple callback example function my_callback_function() { echo 'hello world!'; } call_user_func('my_callback_function'); // method callback examples class MyClass { function myCallbackMethod() { echo 'Hello World!'; } } // static class method call without instantiating an object call_user_func(array('MyClass', 'myCallbackMethod')); // object method call $obj = new MyClass(); call_user_func(array(&$obj, 'myCallbackMethod')); ?>

Type Casting

Type casting in PHP works much as it does in C: the name of the desired type is written in parentheses before the variable which is to be cast.

<?php
$foo = 10;   // $foo is an integer
$bar = (boolean) $foo;   // $bar is a boolean
?>

The casts allowed are:

• (int), (integer) - cast to integer

• (bool), (boolean) - cast to boolean

• (float), (double), (real) - cast to float

• (string) - cast to string

• (array) - cast to array

• (object) - cast to object

Note that tabs and spaces are allowed inside the parentheses, so the following are functionally equivalent:

<?php
$foo = (int) $bar;
$foo = ( int ) $bar;
?>

It may not be obvious exactly what will happen when casting between certain types. For more info, see these sections:

• Converting to boolean

• Converting to integer

• Converting to float

• Converting to string

• Converting to array

• Converting to object

• Converting to resource

• The type comparison tables

The global keyword

First, an example use of global:

Príklad 7-1. Using global <?php $a = 1; $b = 2; function Sum() { global $a, $b; $b = $a + $b; } Sum(); echo $b; ?>

The above script will output "3". By declaring $a and $b global within the function, all references to either variable will refer to the global version. There is no limit to the number of global variables that can be manipulated by a function.

A second way to access variables from the global scope is to use the special PHP-defined $GLOBALS array. The previous example can be rewritten as:

Príklad 7-2. Using $GLOBALS instead of global <?php $a = 1; $b = 2; function Sum() { $GLOBALS["b"] = $GLOBALS["a"] + $GLOBALS["b"]; } Sum(); echo $b; ?>

The $GLOBALS array is an associative array with the name of the global variable being the key and the contents of that variable being the value of the array element. Notice how $GLOBALS exists in any scope, this is because $GLOBALS is a superglobal. Here's an example demonstrating the power of superglobals:

Príklad 7-3. Example demonstrating superglobals and scope <?php function test_global() { // Most predefined variables aren't "super" and require // 'global' to be available to the functions local scope. global $HTTP_POST_VARS; echo $HTTP_POST_VARS['name']; // Superglobals are available in any scope and do // not require 'global'. Superglobals are available // as of PHP 4.1.0 echo $_POST['name']; } ?>

Using static variables

Another important feature of variable scoping is the static variable. A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope. Consider the following example:

Príklad 7-4. Example demonstrating need for static variables <?php function Test () { $a = 0; echo $a; $a++; } ?>

This function is quite useless since every time it is called it sets $a to 0 and prints "0". The $a++ which increments the variable serves no purpose since as soon as the function exits the $a variable disappears. To make a useful counting function which will not lose track of the current count, the $a variable is declared static:

Príklad 7-5. Example use of static variables <?php function Test() { static $a = 0; echo $a; $a++; } ?>

Now, every time the Test() function is called it will print the value of $a and increment it.

Static variables also provide one way to deal with recursive functions. A recursive function is one which calls itself. Care must be taken when writing a recursive function because it is possible to make it recurse indefinitely. You must make sure you have an adequate way of terminating the recursion. The following simple function recursively counts to 10, using the static variable $count to know when to stop:

Príklad 7-6. Static variables with recursive functions <?php function Test() { static $count = 0; $count++; echo $count; if ($count < 10) { Test (); } $count--; } ?>

References with global and static variables

The Zend Engine 1, driving PHP 4, implements the static and global modifier for variables in terms of references. For example, a true global variable imported inside a function scope with the global statement actually creates a reference to the global variable. This can lead to unexpected behaviour which the following example addresses:

<?php
function test_global_ref() {
    global $obj;
    $obj = &new stdclass;
}

function test_global_noref() {
    global $obj;
    $obj = new stdclass;
}

test_global_ref();
var_dump($obj);
test_global_noref();
var_dump($obj);
?>

Executing this example will result in the following output:

NULL
object(stdClass)(0) {
}

A similar behaviour applies to the static statement. References are not stored statically:

<?php
function &get_instance_ref() {
    static $obj;

    echo "Static object: ";
    var_dump($obj);
    if (!isset($obj)) {
        // Assign a reference to the static variable
        $obj = &new stdclass;
    }
    $obj->property++;
    return $obj;
}

function &get_instance_noref() {
    static $obj;

    echo "Static object: ";
    var_dump($obj);
    if (!isset($obj)) {
        // Assign the object to the static variable
        $obj = new stdclass;
    }
    $obj->property++;
    return $obj;
}

$obj1 = get_instance_ref();
$still_obj1 = get_instance_ref();
echo "\n";
$obj2 = get_instance_noref();
$still_obj2 = get_instance_noref();
?>

Executing this example will result in the following output:

Static object: NULL
Static object: NULL

Static object: NULL
Static object: object(stdClass)(1) {
  ["property"]=>
  int(1)
}

This example demonstrates that when assigning a reference to a static variable, it's not remembered when you call the &get_instance_ref() function a second time.

HTML Forms (GET and POST)

When a form is submitted to a PHP script, the information from that form is automatically made available to the script. There are many ways to access this information, for example:

Príklad 7-8. A simple HTML form <form action="foo.php" method="post"> Name: <input type="text" name="username" /><br /> Email: <input type="text" name="email" /><br /> <input type="submit" name="submit" value="Submit me!" /> </form>

Depending on your particular setup and personal preferences, there are many ways to access data from your HTML forms. Some examples are:

Príklad 7-9. Accessing data from a simple POST HTML form <?php // Available since PHP 4.1.0 echo $_POST['username']; echo $_REQUEST['username']; import_request_variables('p', 'p_'); echo $p_username; // Available since PHP 3. As of PHP 5.0.0, these long predefined // variables can be disabled with the register_long_arrays directive. echo $HTTP_POST_VARS['username']; // Available if the PHP directive register_globals = on. As of // PHP 4.2.0 the default value of register_globals = off. // Using/relying on this method is not preferred. echo $username; ?>

Using a GET form is similar except you'll use the appropriate GET predefined variable instead. GET also applies to the QUERY_STRING (the information after the '?' in a URL). So, for example, http://www.example.com/test.php?id=3 contains GET data which is accessible with $_GET['id']. See also $_REQUEST and import_request_variables().

As shown, before PHP 4.2.0 the default value for register_globals was on. And, in PHP 3 it was always on. The PHP community is encouraging all to not rely on this directive as it's preferred to assume it's off and code accordingly.

PHP also understands arrays in the context of form variables (see the related faq). You may, for example, group related variables together, or use this feature to retrieve values from a multiple select input. For example, let's post a form to itself and upon submission display the data:

Príklad 7-10. More complex form variables <?php if (isset($_POST['action']) && $_POST['action'] == 'submitted') { echo '<pre>'; print_r($_POST); echo '<a href="'. $_SERVER['PHP_SELF'] .'">Please try again</a>'; echo '</pre>'; } else { ?> <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post"> Name: <input type="text" name="personal[name]" /><br /> Email: <input type="text" name="personal[email]" /><br /> Beer: <br /> <select multiple name="beer[]"> <option value="warthog">Warthog</option> <option value="guinness">Guinness</option> <option value="stuttgarter">Stuttgarter Schwabenbräu</option> </select><br /> <input type="hidden" name="action" value="submitted" /> <input type="submit" name="submit" value="submit me!" /> </form> <?php } ?>

In PHP 3, the array form variable usage is limited to single-dimensional arrays. In PHP 4, no such restriction applies.

<input type="image" src="image.gif" name="sub" />

HTTP Cookies

PHP transparently supports HTTP cookies as defined by Netscape's Spec. Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users. You can set cookies using the setcookie() function. Cookies are part of the HTTP header, so the SetCookie function must be called before any output is sent to the browser. This is the same restriction as for the header() function. Cookie data is then available in the appropriate cookie data arrays, such as $_COOKIE, $HTTP_COOKIE_VARS as well as in $_REQUEST. See the setcookie() manual page for more details and examples.

If you wish to assign multiple values to a single cookie variable, you may assign it as an array. For example:

<?php
  setcookie("MyCookie[foo]", "Testing 1", time()+3600);
  setcookie("MyCookie[bar]", "Testing 2", time()+3600);
?>

That will create two separate cookies although MyCookie will now be a single array in your script. If you want to set just one cookie with multiple values, consider using serialize() or explode() on the value first.

Note that a cookie will replace a previous cookie by the same name in your browser unless the path or domain is different. So, for a shopping cart application you may want to keep a counter and pass this along. i.e.

<?php
if (isset($_COOKIE['count'])) {
    $count = $_COOKIE['count'] + 1;
} else {
    $count = 1;
}
setcookie("count", $count, time()+3600);
setcookie("Cart[$count]", $item, time()+3600);
?>

Dots in incoming variable names

Typically, PHP does not alter the names of variables when they are passed into a script. However, it should be noted that the dot (period, full stop) is not a valid character in a PHP variable name. For the reason, look at it:

<?php $varname.ext; /* invalid variable name */ ?>

Now, what the parser sees is a variable named $varname, followed by the string concatenation operator, followed by the barestring (i.e. unquoted string which doesn't match any known key or reserved words) 'ext'. Obviously, this doesn't have the intended result.

For this reason, it is important to note that PHP will automatically replace any dots in incoming variable names with underscores.

Determining variable types

Because PHP determines the types of variables and converts them (generally) as needed, it is not always obvious what type a given variable is at any one time. PHP includes several functions which find out what type a variable is, such as: gettype(), is_array(), is_float(), is_int(), is_object(), and is_string(). See also the chapter on Types.