PHP: var_dump - Manual

Description

void var_dump ( mixed expression [, mixed expression [, ...]] )

This function displays structured information about one or more expressions that includes its type and value. Arrays and objects are explored recursively with values indented to show structure.

In PHP 5 only public, private and protected properties of objects will be returned in the output.

Tip: As with anything that outputs its result directly to the browser, you can use the output-control functions to capture the output of this function, and save it in a string (for example).

Examples

Example 1. var_dump() example

<?php $a = array(1, 2, array("a", "b", "c")); var_dump($a); ?>
The above example will output:
array(3) { [0]=> int(1) [1]=> int(2) [2]=> array(3) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" } }

<?php $b = 3.1; $c = true; var_dump($b, $c); ?>
The above example will output:
float(3.1) bool(true)

User Contributed Notes
var_dump

Christian Riesen
09-May-2005 05:41


There is a small quirk in it, obviously it first does the var_dump if its in the same line with other commands.



Example:

<?php

$array = array(1,2,3);



// Does not work? Shows first the var_dump, then <pre>

echo "<pre>" . var_dump($array);



// Works perfectly as intended

echo "<pre>";

echo var_dump($array);

?>



Also, output control is not the best way to catch the output, instead, using

$output = var_export($variable,TRUE); 

fills the $output variable with just the same. See the var_export() documentation for details.

edwardzyang at thewritingpot dot com
20-Mar-2005 05:06


If you're like me and uses var_dump whenever you're debugging, you might find these two "wrapper" functions helpful.



This one automatically adds the PRE tags around the var_dump output so you get nice formatted arrays.



<?php



function var_dump_pre($mixed = null) {

  echo '<pre>';

  var_dump($mixed);

  echo '</pre>';

  return null;

}



?>



This one returns the value of var_dump instead of outputting it.



<?php



function var_dump_ret($mixed = null) {

  ob_start();

  var_dump($mixed);

  $content = ob_get_contents();

  ob_end_clean();

  return $content;

}



?>



Fairly simple functions, but they're infinitely helpful (I use var_dump_pre() almost exclusively now).

dwatson at planandgrow dot com
09-Mar-2005 07:02


To make sure to get the nice indenting of nested arrays, you may have to put html-<pre> tags around the var_dump():



Where $a is an array--

echo "<pre>";

var_dump($a);

echo "</pre>";

anon
28-Jan-2005 09:31


var_dump(get_defined_vars());

will dump all defined variables to the browser.

var_dump

Description

Parameters

Return Values

Examples

See Also