Where php.ini locate?

Create a phpinfo.php inside root directory
with the below content
// Show all information, defaults to INFO_ALL
phpinfo();
// Show just the module information.//
phpinfo(8) yields identical results.
phpinfo(INFO_MODULES);
?>

run from IE
http://localhost/phpinfo.php

You will get php information from the page display
one of the information is php.ini path
"Configuration File (php.ini) Path"