List all PHP variables

Question

Is it possible to dump all global variables in a PHP script? Say this is my code:

<?php
$foo = 1;
$bar = "2";
include("blah.php");
dumpall();
// displays $foo, $bar and all variables created by blah.php

Also, is it possible to dump all defined constants in a PHP script.

Solution 1

Use get_defined_vars and/or get_defined_constants

$arr = get_defined_vars();
print_r($arr);

Solution 2

When debugging trying to find differences using a program such as WinMerge (freeware) to see what differences various arrays and variables have you'll want to ksort() otherwise you'll get lots of false negatives. It also helps to visually format using the HTML pre element...

<?php
$everything = get_defined_vars();
ksort($everything);

?>

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Edit: had to come back to this and realized I had a better answer, $GLOBALS.

$a = print_r(var_dump($GLOBALS),1);
echo '<pre>';
echo htmlspecialchars($a);
echo '</pre>';

---

Edit 2: as mpag mentioned print_r() may be susceptible to running out of memory if the software you're working with uses a lot. Presuming there is no output or it's clearly truncated and you have access to the php.ini file you can adjust the memory use as so:

ini_set('memory_limit', '1024M');

Comments

[Long Ears]

and get_defined_constants for constants

[Salman A]

$nico: Does this also work for variables created inside eval()?

[Lienau]

@Salman As long as get_defined_vars()/get_defined_constants() is called after the eval(), then yes.

[JaseC]

Just for those who are copy/pasting and want this in one line echo "<pre>"; print_r(get_defined_vars()); die; Copy whatever of that you want.

[quantme]

This answer is gold for me.

[mpag]

three comments: 1) print_r runs out of memory when using a class-heavy CMS, but json_encode($GLOBALS) with console.logging javascript works. 2) Don't forget the $_ variables (SERVER, SESSION, ENV, FILES, COOKIE, GET, POST, REQUEST). 3) for more in-depth debugging i also do a get_declared_classes and iterate though those to get_class_vars and get_class_methods

[John]

@mpag Ah yes, I've seen some software use ludicrous amounts of memory; apparently the work around for that is to obviously either not use such a system but a lot of folks won't have that option so stackoverflow.com/a/16423653/606371 will hopefully work for them. Also if I recall correctly the $_ variables should be pulled from $GLOBALS. Thanks for your comment, I'll look in to get_declared_classes and get_class_vars soon. :-)

[mpag]

I'm already setting my limit to 512M, and I believe it's unlikely that doubling to 1024 will resolve this issue in my case. I believe 2048M is the hard limit for php.