1. Getting Prepared

If you have already installed PHP 5 onto your server (or just your own Windows PC for local development) then please ensure that you have also done the following three things, otherwise the majority of the extensions available to you will always fail to load.

1) You must have updated your php.ini file so that the extension_dir line points to the actual folder where the DLL files live. See section 1.1 if you've not done this.

2) You must add the location of your PHP installation to your PATH Environment variable. If you have not done this, you are asking for a world of pain, so please jump directly to section 1.2 and follow the instructions there.

3) Create a simple script with nothing more than a call to phpinfo(); in it, and then load this page each time you make a change to ensure it actually worked.

Note: I never 'install' PHP using the Windows Installer on the PHP site, because I find it far easier to just download the ZIP version and configure Apache manually. This doesn't mean you shouldn't, it just means don't be scared of grabbing the ZIP archive instead and trying to do it 'by hand', you'll learn a lot about how it all works and you'll appreciate it's actually very simple to get running.

1.1 - The extension_dir value

Within your php.ini file there is a value called extension_dir. By default it points to ./, which is of little use if you need to actually load some extensions. So change it to point to the ext folder that was installed with PHP 5. On my installation for example the line looks like this:

But you will need to change the path to match where you've installed PHP. You do NOT include the trailing slash at the end, and use forward-slashes (as above). Incase you were wondering, the reason I have my PHP 5 installation within a folder called 'php' is because I have lots of different versions of PHP in there.. 4.4.4, 4.4.5, 5.2.1, etc. All in the one 'php' folder and then a sub-folder for each there-of. It allows me to swap between PHP versions quickly with a simple Apache conf file change + restart.

1.2 - The PATH Environment Variable

PHP 5 comes with a lot of extensions (DLLs) pre-loaded into the ext folder. However a large number of these DLL files have dependencies on other DLLs in order to work. A lot of these other DLLs can be found in the root PHP folder. For example if you look in the folder where you installed PHP you will notice files in there such as libeay32.dll and msql.dll. These are libraries used by one or more of the extensions.

However, although you've set your extension_dir to point to the ext folder (if and you haven't, see section 1.1), the DLLs themselves don't know where to look for the libraries they are dependent on. They leave it up to Windows to scan for them automatically. Windows will only check in a few directories by default, one of them being the windows/system32 folder - which is why you see lots of guides on the web telling you to copy this, that and the other into the system32 folder. I will advise you strongly against this. First it messes up your Windows installation, second it isn't required, and third it makes it much harder to keep track of what on earth you've done and what is loading from where.

A much easier solution is to add your PHP root directory to the list of locations that Windows will search for required libraries. Doing this is easy:

Windows 2000 / XP / 2003: Right-click on your 'My Computer' icon on your Desktop and select 'Properties' (if you don't have your 'My Computer' icon enabled, go to the Control Panel and click 'System'). Click the 'Advanced' tab and at the bottom is a button labeled 'Environment Variables'.

Windows Vista: Right-click on your 'Computer' icon on your Desktop and select the text link 'Advanced System Settings' on the left menu. You'll then see a new window appear which should default to the Advanced tab already, and at the bottom is a button labeled 'Environment Variables'.

Click the 'Environment Variables' button.

You need to find the 'Path' Variable on the SYSTEM VARIABLES list (not the User Variables). Select it and click 'Edit'. To add a new path go to the end of the entries already there and insert a semi-colon (;) followed by the location of your root PHP directory. On my Windows server that means I added: ";C:\php\php521" to the end, but this will vary depending on where you installed PHP.

Once done click OK and confirm your way out of all the dialogs until you're back in Windows. Now reboot. This is a vital step and cannot be ignored, regardless of which version of Windows you're using. When Windows comes back up again it will now look in the directory you just added for dynamic library files, which is exactly what we need.

2. The Extensions List

To use an extension you nearly always just have to uncomment the line in your php.ini file. To do this just remove the semi-colon from the start of the line. Where there are extra conditions I have mentioned them below.

Here we go.. every single default extension, broken down with dependencies where applicable.

php_curl.dll

This DLL uses libeay32.dll and ssleay32.dll, which are included with PHP5, so will work only providing your PATH setting is correct.

php_ldap.dll

This DLL uses libeay32.dll and ssleay32.dll, which are included with PHP5, so will work only providing your PATH setting is correct.

php_openssl.dll

This DLL uses libeay32.dll and ssleay32.dll, which are included with PHP5, so will work only providing your PATH setting is correct.

php_msql.dll

This uses msql.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_mhash.dll

This uses libmhash.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_interbase.dll

This uses gds32.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_fdf.dll

This uses fdftk.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_mcrypt.dll

This uses libmcrypt.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_mssql.dll

This uses ntwdblib.dll, which is included with PHP5 so will work providing your PATH setting is correct.

php_exif.dll

This extension requires that you load php_mbstring.dll BEFORE it. So move the line: extension=php_mbstring.dll ABOVE the extension=php_exif.dll line.

php_ifx.dll

This is the Informix driver, and it needs isqlt09a.dll (i.e. it needs the Informix libraries installed locally)

php_mysql.dll

php_mysqli.dll

Both require libmysql.dll in your PHP root directory. If this doesn't exist, copy it from the MySQL/bin directory assuming you have MySQL installed locally. If not then download it, install it, get the DLL you require, then you can remove MySQL again if you want. You could also add the MySQL/bin directory to your Path environment variable if you so wished.

php_pdo_mysql.dll

Requires libmysql.dll the same as php_mysqli.dll does. ALSO you MUST uncomment php_pdo.dll in your php.ini file in order to use any of the PDO extensions, and it must come BEFORE the database DLLs. This is a CORRECT PDO set-up:

extension=php_pdo.dll
extension=php_pdo_mysql.dll
extension=php_pdo_pgsql.dll
extension=php_pdo_sqlite.dll

The above loads PDO, then adds in the MySQL, Postgres and SQLite modules. The order is vitally important.

php_pdo_firebird.dll

This uses gds32.dll, which is included with PHP5 so will work providing your PATH setting is correct. Requires that php_pdo.dll is uncommented and higher-up the extension list.

php_pdo_mssql.dll

php_pdo_odbc.dll

php_pdo_pgsql.dll

php_pdo_sqlite.dll

All of these requires that php_pdo.dll is uncommented and higher-up the extension list than they are.

php_oci8.dll

php_pdo_oci.dll

Updated thanks to new info from Chris Jones: These two require that you have the Oracle 10g client libraries installed.

php_pdo_oci8.dll

Updated thanks to new info from Chris Jones: This version of the DLL is built to work with Oracle 8+ client libraries (and thus will require them installed).

php_pspell.dll

To use the PSPell library you will need two DLL files from the GNU Aspell Win32 version. Download the latest full Win32 installer from http://aspell.net/win32/ and install it. Then copy the two DLL files found in C:\Program Files\Aspell\bin (aspell-15.dll and pspell-15.dll) into your root PHP directory. You can then use this extension.

php_sybase_ct.dll

This requires you have the Sybase Open Client libraries installed on the server.

The following all work without any dependencies

php_bz2.dll
php_dba.dll
php_dbase.dll
php_gettext.dll
php_gd2.dll
php_gmp.dll
php_imap.dll
php_mime_magic.dll
php_ming.dll
php_pgsql.dll
php_shmop.dll
php_snmp.dll
php_soap.dll
php_sockets.dll
php_sqlite.dll
php_tidy.dll
php_xmlrpc.dll
php_xsl.dll
php_zip.dll

Phew

There we go! That is all of the DLLs that ship with PHP 5 covered. As you can see, most of them will cause you very little problems as long as your environment is set-up correctly to begin with. The php.ini ordering is a bit of a catch-out, and in my opinion ought to be mentioned in the php.ini comments somewhere, as it's vital to getting some of these extensions working.

Hope you find this useful.