How to Install and Configure PHP 5 to Run with Apache on Windows

Steps to Setting Up PHP 5

1. Download PHP 5

   Before you begin, get a copy of PHP 5 from the PHP download page. In particular, download the VC6 thread-safe zip package from the "Windows Binaries" section — that is, don't get the installer. For example, select the package labelled "PHP 5.2.5 zip package" if 5.2.5 is the current version.
   [Update: note that I have not tested the procedure below with any of the PHP 5.3 versions, only with 5.2.5, which was the latest version at the time I originally wrote this. In theory, the procedure should work with later 5.2 versions as well. I'm not sure about 5.3 though. A version jump from 5.2 to 5.3 usually means bigger changes than simple bug fixes. If you want to be sure the procedure below will work, just get the latest of the 5.2 series.]

2. Install PHP 5

   Create a folder on your hard disk for PHP. I suggest "c:\php" although you can use other names if you wish. Personally though, I prefer to avoid names with spaces in it, like "c:\Program Files\php" to avoid potential problems with programs that cannot handle such things. I will assume that you used c:\php in this tutorial.
   Extract all the files from the zip package into that folder. To do that simply double-click the zip file to open it, and drag all the files and folders to c:\php.

3. Upgraders: Remove the Old PHP.INI File from Your Windows Directory

   If you are upgrading to PHP 5 from an older version, go to your windows directory, typically c:\windows, and delete any php.ini file that you have previously placed there.

4. Configuring PHP

   Go to the c:\php folder and make a copy of the file "php.ini-recommended". Name the new file "php.ini". That is, you should now have a file "c:\php\php.ini", identical in content with "c:\php\php.ini-recommended".
   Note: if you are using Apache 1, you should either move the php.ini file to your windows directory, "C:\Windows" on most systems, or configure your PATH environment variable to include "c:\php". If you don't know how to do the latter, just move the php.ini file to the "c:\windows" folder. You do not have to do this if you are using Apache 2, since we will include a directive later in the Apache 2 configuration file to specify the location of the php.ini file.
   Use an ASCII text editor (such as Notepad, which can be found in the Accessories folder of your Start menu) to open "php.ini". You may need to make the following changes to the file, depending on your requirements:

   1. Enable Short Open Tags

      Search for the line that reads:
      
      short_open_tag = Off
      If short_open_tag is set to "off", tags like "commercial web hosts that support PHP have no issues with your scripts using "

   2. Display Errors

      On a "live" website, you typically want errors in your script to be silently logged to a PHP error file. On your own local machine, however, while you are testing and debugging a PHP script, it is probably more convenient to have error messages sent to the browser window when they appear. This way, you won't miss errors if you forget to check the error log file.
      If you want PHP to display error messages in your browser window, look for the following:
      
      display_errors = Off
      And change it to:
      
      display_errors = On
      This value should always be set to "Off" for a "live" website.

   3. Session Path

      If your script uses sessions, look for the following line:
      
      ;session.save_path = "/tmp"
      The session.save_path sets the folder where PHP saves its session files. Since "/tmp" does not exist on Windows, you will need to set it to a directory that does. One way is to create a folder called (say) "c:\tmp" (the way you created c:\php earlier), and point this setting to that folder. If you do that, change the line to the following:
      
      session.save_path = "c:\tmp"
      Notice that in addition to changing the path, I also removed the semi-colon (";") prefix from the line.
      Alternatively, you can find out the current TEMP folder on your computer and use that. Or create a "tmp" folder in your PHP directory, like "c:\php\tmp" and set the configuration file accordingly. The possibilities are endless. If you can't decide, just create "c:\tmp" and do as I said above.

   4. SMTP Server

      If your script uses the mail() function, and you want the function to successfully send mail on your local machine, look for the following section:
      
      [mail function]
      ; For Win32 only.
      SMTP = localhost
      smtp_port = 25
      
      ; For Win32 only.
      ;sendmail_from = me@example.com
      Change it to point to your SMTP server and email account. For example, if your SMTP server is "mail.example.com" and your email address is "youremail@example.com", change the code to:
      
      [mail function]
      SMTP = mail.example.com
      smtp_port = 25
      sendmail_from = youremail@example.com
      Note that after you do this, when your script tries to use the mail() function, you will need to be connected to your ISP for the function to succeed. If you do not modify the above lines and attempt to use mail() in your script, the function will return a fail code, and display (or log) the error (depending on how you configure php.ini to handle errors).
      (Note that in Apache 1.x, the smtp_port line may not be present. If so, don't include it.)

creditby: Christopher Heng, thesitewizard.com