Open XAMPP Control Panel, hit on the "Help" button and then "View ReadMe" ... It'll open a Notepad file having the first line as:
"###### ApacheFriends XAMPP Version x.y.x ######"
where x.y.z is the XAMPP version!
Answer from user3310092 on Stack OverflowOpen XAMPP Control Panel, hit on the "Help" button and then "View ReadMe" ... It'll open a Notepad file having the first line as:
"###### ApacheFriends XAMPP Version x.y.x ######"
where x.y.z is the XAMPP version!
Go to uninstall software if you are on windows and there you will see the version of your xammp.

Run in command line
<xampp_dir>\apache\bin\httpd -v
It prints Apache version.
For example I had installed XAMPP to C:\Aplikace\xampp directory and type into Command Line
C:\Aplikace\xampp\apache\bin\httpd -v
that responsed

- Go to xampp folder where you installed xampp
- Find apache?
- xampp->apache->bin->httpd->right click->properties->details->version find php version in xampp
- xampp control panel which, after the complete installation, contains start, stop, config, etc.
- There you find shell-> click->type php-v
- mariaDB version in xampp?
- Type localhost/phpmyadmin after installation on url
- Find sql
- Type select version(); and hit enter
Videos
If you are using new version of xampp.
Try http://localhost/dashboard/phpinfo.php
Put this code in your root directory or htdocs folder of xampp:
<?php phpinfo(); ?>- Save it as phpinfo.php and point your browser to it (this could be http://localhost/phpinfo.php)
- Example: random image (Click Here)
Put this in your root directory:
<?php
phpinfo();
?>
Save it as phpinfo.php and point your browser to it (this could be http://localhost/phpinfo.php)
- More information (you can get much more information than just the version).
- Example (random image):

Try with command from terminal
sudo /opt/lampp/bin/php -v
The version will be published in the log specified under ErrorLog within your configuration. (/var/log/httpd/error_log is a standard location in many Linuxes.)
Additionally, you should be able to execute the httpd binary equivalent in windows with -v.
Example from Linux:
# /usr/local/apache/bin/httpd -v
Server version: Apache/1.3.41 (Unix)
Server built: Sep 10 2009 10:42:36
From CMD:
"C:\Program Files\[Apache directories]\bin\httpd.exe" -v
Example:
C:\Documents and Settings\User>"c:\Program Files\Apache Software Foundation\Apache2.2\bin\httpd.exe" -v
Server version: Apache/2.2.21 (Win32)
Server built: Sep 9 2011 10:26:10
Please note
This answer is not valid for new version of XAMPP.
First, you'll need to stop Apache from XAMPP. Then,
Go go cmd and switch to your XAMPP folder. For example, if your XAMPP folder is in C:\
C:\>cd C:\XAMPP
In this folder is a file named php-switch.bat, run from the command line. If not, you can also run php-switch.bat directly.
You'll see the version you are now on, and procedure to switch. For example, type 4 to switch PHP 4 then follow the procedure.

PHP 4 will install in your XAMPP\PHP directory and successfully switch. then re-enable the Apache.
The best method is to change the PHP settings in
/apache/conf/extra/httpd-xampp.conf
to reflect the new version of PHP you want to use
In my case I unpacked PHP5.4 to C:\XAMPPLITE\PHP5.4 and then updated key lines in this file such as:
SetEnv PHPRC "C:\\xampplite\\php5.4"
LoadFile "C:/xampplite/php5.4/php5ts.dll"
PHPINIDir "C:/xampplite/php5.4"
You also need to ensure that the correct version of php5apache2_2.dll is installed
To ensure this I copied the new version of php5apache2_2.dll to the Apache modules directory with a unique name, and then modified the configuration to match that:
copy php5.4\php5apache2_2.dll apache\modules\php5apache2_2-5_4.dll
and in the httpd-xampp.conf file
LoadModule php5_module modules/php5apache2_2-5_4.dll