PHP: How to check whether a library has been properly installed and enabled?

Question

Following another question on SO (I am no PHP expert), I am wondering whether the Zlib library has been properly installed on my local laptop. Documentation says there shoul

Answer 1

Make sure that, if you are using DevDesktop, you are referencing the Application/Devdesktop/php# version of PHP(links within DD prefs) (my dev machine has three: Mac OS, HomeBrew, and Acquia DevD)..

I used Homebrew to tap that ^ keg and install the plugin (Mac).

Answer 2

Unless I'm missing something:

var_dump(function_exists('gzclose')); // or any gz-related functions

Or to be more specific and correct

if(extension_loaded('zlib'))

http://sg.php.net/manual/en/function.extension-loaded.php

Answer 3

You can use phpinfo() to get full information about libraries

<?php
   phpinfo();
?>

or in your PHP code test for a given function

if (function_exists("gzcompress")) {
  echo "OK";
} else {
  die("zlib missing");
}