Copy/paste this into the top of your web page or save the code as phpDebugTool.php and then include it using include("phpDebugTool.php");. Then look at the source code after you’ve run the page.

<?php
	/* These lines format the output as HTML comments and call dump_array repeatedly */
	echo "\n<!-- BEGIN VARIABLE DUMP -->\n\n";
	echo "\n\n<!-- BEGIN GET VARS -->\n\n";echo "<!-- ".dump_array($_GET)." -->\n";
	echo "\n\n<!-- BEGIN POST VARS -->\n\n";echo "<!-- ".dump_array($_POST)." -->\n";
	echo "\n\n<!-- BEGIN SESSION VARS -->\n\n";echo "<!-- ".dump_array($_SESSION)." -->\n";
	echo "\n\n<!-- BEGIN COOKIE VARS -->\n\n";echo "<!-- ".dump_array($_COOKIE)." -->\n";
	echo "\n\n<!-- END VARIABLE DUMP -->\n\n";
	function dump_array($array) {
		if(is_array($array)) {
			$size = count($array);
			$string = "";
			if ($size) {
				$count = 0;
				$string .= "{ ";
				//loop thru key:value pairs
				foreach($array as $var => $value) {
					$string .= $var." = ".$value;
					if($count++ < ($size-1)) {
						$string .= ", ";
					}
				}
				$string .= " }";
			}
			return $string;
		} else {
			return $array;
		}
	}
	?>

An example of this in action can been seen on the Demo page.