Keep in mind if you have xdebug installed it will limit the var_dump() output of array elements and object properties to 3 levels deep.
To change the default, edit your xdebug.ini file and add the folllowing line:
xdebug.var_display_max_depth=n
More information here:
http://www.xdebug.org/docs/display
PHP - Manual: var_dump
2024-12-22
var_dump
(PHP 4, PHP 5, PHP 7, PHP 8)
var_dump — 打印变量的相关信息
说明
此函数显示关于一个或多个表达式的结构信息，包括表达式的类型与值。数组和对象将递归展开值，通过缩进显示其结构。
对象的所有公共、私有和受保护的属性都会在输出中返回，除非该对象实现了 __debugInfo() 方法。
小技巧
和直接将结果输出到浏览器一样，可使用输出控制函数来捕获当前函数的输出，然后(例如)保存到一个 string 中。
参数
-
value -
要打印的表达式。
-
values -
更多要打印的表达式。
返回值
没有返回值。
范例
示例 #1 var_dump() 例子
<?php
$a = array(1, 2, array("a", "b", "c"));
var_dump($a);
?>
以上例程会输出：
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, $c);
?>
以上例程会输出：
float(3.1) bool(true)
参见
- print_r() - 以易于理解的格式打印变量。
- debug_zval_dump() - Dumps a string representation of an internal zval structure to output
- var_export() - 输出或返回变量的可解析字符串表示
- __debugInfo()
add a note
User Contributed Notes 16 notes
rich dot schu at gmail dot com ¶
14 years ago
edwardzyang at thewritingpot dot com ¶
17 years ago
If you're like me and uses var_dump whenever you're debugging, you might find these two "wrapper" functions helpful.
This one automatically adds the PRE tags around the var_dump output so you get nice formatted arrays.
<?php
function var_dump_pre($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 $content;
}
?>
Fairly simple functions, but they're infinitely helpful (I use var_dump_pre() almost exclusively now).
b dot bergloev at gmail dot com ¶
7 years ago
I post a new var_dump function with colors and collapse features. It can also adapt to terminal output if you execute it from there. No need to wrap it in a pre tag to get it to work in browsers.
<?php
function dump_debug($input, $collapse=false) {
$recursive = function($data, $level=0) use (&$recursive, $collapse) {
global $argv;
$isTerminal = isset($argv);
if (!$isTerminal && $level == 0 && !defined("DUMP_DEBUG_SCRIPT")) {
define("DUMP_DEBUG_SCRIPT", true);
echo '<script language="Javascript">function toggleDisplay(id) {';
echo 'var state = document.getElementById("container"+id).style.display;';
echo 'document.getElementById("container"+id).style.display = state == "inline" ? "none" : "inline";';
echo 'document.getElementById("plus"+id).style.display = state == "inline" ? "inline" : "none";';
echo '}</script>'."\n";
}
$type = !is_string($data) && is_callable($data) ? "Callable" : ucfirst(gettype($data));
$type_data = null;
$type_color = null;
$type_length = null;
switch ($type) {
case "String":
$type_color = "green";
$type_length = strlen($data);
$type_data = "\"" . htmlentities($data) . "\""; break;
case "Double":
case "Float":
$type = "Float";
$type_color = "#0099c5";
$type_length = strlen($data);
$type_data = htmlentities($data); break;
case "Integer":
$type_color = "red";
$type_length = strlen($data);
$type_data = htmlentities($data); break;
case "Boolean":
$type_color = "#92008d";
$type_length = strlen($data);
$type_data = $data ? "TRUE" : "FALSE"; break;
case "NULL":
$type_length = 0; break;
case "Array":
$type_length = count($data);
}
if (in_array($type, array("Object", "Array"))) {
$notEmpty = false;
foreach($data as $key => $value) {
if (!$notEmpty) {
$notEmpty = true;
if ($isTerminal) {
echo $type . ($type_length !== null ? "(" . $type_length . ")" : "")."\n";
} else {
$id = substr(md5(rand().":".$key.":".$level), 0, 8);
echo "<a href=\"javascript:toggleDisplay('". $id ."');\" style=\"text-decoration:none\">";
echo "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span>";
echo "</a>";
echo "<span id=\"plus". $id ."\" style=\"display: " . ($collapse ? "inline" : "none") . ";\"> ⤵</span>";
echo "<div id=\"container". $id ."\" style=\"display: " . ($collapse ? "" : "inline") . ";\">";
echo "<br />";
}
for ($i=0; $i <= $level; $i++) {
echo $isTerminal ? "| " : "<span style='color:black'>|</span> ";
}
echo $isTerminal ? "\n" : "<br />";
}
for ($i=0; $i <= $level; $i++) {
echo $isTerminal ? "| " : "<span style='color:black'>|</span> ";
}
echo $isTerminal ? "[" . $key . "] => " : "<span style='color:black'>[" . $key . "] => </span>";
call_user_func($recursive, $value, $level+1);
}
if ($notEmpty) {
for ($i=0; $i <= $level; $i++) {
echo $isTerminal ? "| " : "<span style='color:black'>|</span> ";
}
if (!$isTerminal) {
echo "</div>";
}
} else {
echo $isTerminal ?
$type . ($type_length !== null ? "(" . $type_length . ")" : "") . " " :
"<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span> ";
}
} else {
echo $isTerminal ?
$type . ($type_length !== null ? "(" . $type_length . ")" : "") . " " :
"<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span> ";
if ($type_data != null) {
echo $isTerminal ? $type_data : "<span style='color:" . $type_color . "'>" . $type_data . "</span>";
}
}
echo $isTerminal ? "\n" : "<br />";
};
call_user_func($recursive, $input);
}
?>
thriller dot ze at gmail dot com ¶
14 years ago
As Bryan said, it is possible to capture var_dump() output to a string. But it's not quite exact if the dumped variable contains HTML code.
You can use this instead:
<?php
echo '<pre>'; // This is for correct handling of newlines
ob_start();
var_dump($var);
$a=ob_get_contents();
ob_end_clean();
echo htmlspecialchars($a,ENT_QUOTES); // Escape every HTML special chars (especially > and < )
echo '</pre>';
?>
kobrasrealm at gmail dot com ¶
10 years ago
I wrote this dandy little function for using var_dump() on HTML documents so I don't have to view the source.
<?php
function htmldump($variable, $height="9em") {
echo "<pre style=\"border: 1px solid #000; height: {$height}; overflow: auto; margin: 0.5em;\">";
var_dump($variable);
echo "</pre>\n";
}
?>
You can pass arguments like this:
<?php
$sql = mysql_query("SELECT id, name, value FROM table WHERE cond = 'value'");
$s = mysql_fetch_assoc($sql);
// Dump variable containing the result of the MySQL query
var_dump($s);
?>
The second parameter lets you specify the height of the box. Default is 9em, but if you're expecting a huge output you'll probably want a higher value.
<?php
var_dump($s, "17em");
?>
Happy var_dumping.
Anonymous ¶
5 years ago
Be careful this outputs to stdout stream (1) instead of the proper stderr stream (2).
stlawson *AT* joyfulearthtech *DOT* com ¶
10 years ago
<?php
/**
* Better GI than print_r or var_dump -- but, unlike var_dump, you can only dump one variable.
* Added htmlentities on the var content before echo, so you see what is really there, and not the mark-up.
*
* Also, now the output is encased within a div block that sets the background color, font style, and left-justifies it
* so it is not at the mercy of ambient styles.
*
* Inspired from: PHP.net Contributions
* Stolen from: [highstrike at gmail dot com]
* Modified by: stlawson *AT* JoyfulEarthTech *DOT* com
*
* @param mixed $var -- variable to dump
* @param string $var_name -- name of variable (optional) -- displayed in printout making it easier to sort out what variable is what in a complex output
* @param string $indent -- used by internal recursive call (no known external value)
* @param unknown_type $reference -- used by internal recursive call (no known external value)
*/
function do_dump(&$var, $var_name = NULL, $indent = NULL, $reference = NULL)
{
$do_dump_indent = "<span style='color:#666666;'>|</span> ";
$reference = $reference.$var_name;
$keyvar = 'the_do_dump_recursion_protection_scheme'; $keyname = 'referenced_object_name';
// So this is always visible and always left justified and readable
echo "<div style='text-align:left; background-color:white; font: 100% monospace; color:black;'>";
if (is_array($var) && isset($var[$keyvar]))
{
$real_var = &$var[$keyvar];
$real_name = &$var[$keyname];
$type = ucfirst(gettype($real_var));
echo "$indent$var_name <span style='color:#666666'>$type</span> = <span style='color:#e87800;'>&$real_name</span><br>";
}
else
{
$var = array($keyvar => $var, $keyname => $reference);
$avar = &$var[$keyvar];
$type = ucfirst(gettype($avar));
if($type == "String") $type_color = "<span style='color:green'>";
elseif($type == "Integer") $type_color = "<span style='color:red'>";
elseif($type == "Double"){ $type_color = "<span style='color:#0099c5'>"; $type = "Float"; }
elseif($type == "Boolean") $type_color = "<span style='color:#92008d'>";
elseif($type == "NULL") $type_color = "<span style='color:black'>";
if(is_array($avar))
{
$count = count($avar);
echo "$indent" . ($var_name ? "$var_name => ":"") . "<span style='color:#666666'>$type ($count)</span><br>$indent(<br>";
$keys = array_keys($avar);
foreach($keys as $name)
{
$value = &$avar[$name];
do_dump($value, "['$name']", $indent.$do_dump_indent, $reference);
}
echo "$indent)<br>";
}
elseif(is_object($avar))
{
echo "$indent$var_name <span style='color:#666666'>$type</span><br>$indent(<br>";
foreach($avar as $name=>$value) do_dump($value, "$name", $indent.$do_dump_indent, $reference);
echo "$indent)<br>";
}
elseif(is_int($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".htmlentities($avar)."</span><br>";
elseif(is_string($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color\"".htmlentities($avar)."\"</span><br>";
elseif(is_float($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".htmlentities($avar)."</span><br>";
elseif(is_bool($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".($avar == 1 ? "TRUE":"FALSE")."</span><br>";
elseif(is_null($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> {$type_color}NULL</span><br>";
else echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> ".htmlentities($avar)."<br>";
$var = $var[$keyvar];
}
echo "</div>";
}
?>
php at mikeboers dot com ¶
14 years ago
Howdy!
I am working on a pretty large project where I needed to dump a human readable form of whatever into the log files... and I thought var_export was too difficult to read. BigueNique at yahoo dot ca has a nice solution, although I needed to NOT modify whatever was being passed to dump.
So borrowing heavily from BigueNique's (just reworked his function) and someone's idea over in the object cloning page, I came up with the following function.
It makes a complete copy of whatever object you initially pass it, including all recursive definitions and outside objects references, then does the same thing as BigueNique's function. I also heavily reworked what it output, to suit my needs.
<?php
function var_log(&$varInput, $var_name='', $reference='', $method = '=', $sub = false) {
static $output ;
static $depth ;
if ( $sub == false ) {
$output = '' ;
$depth = 0 ;
$reference = $var_name ;
$var = serialize( $varInput ) ;
$var = unserialize( $var ) ;
} else {
++$depth ;
$var =& $varInput ;
}
// constants
$nl = "\n" ;
$block = 'a_big_recursion_protection_block';
$c = $depth ;
$indent = '' ;
while( $c -- > 0 ) {
$indent .= '| ' ;
}
// if this has been parsed before
if ( is_array($var) && isset($var[$block])) {
$real =& $var[ $block ] ;
$name =& $var[ 'name' ] ;
$type = gettype( $real ) ;
$output .= $indent.$var_name.' '.$method.'& '.($type=='array'?'Array':get_class($real)).' '.$name.$nl;
// havent parsed this before
} else {
// insert recursion blocker
$var = Array( $block => $var, 'name' => $reference );
$theVar =& $var[ $block ] ;
// print it out
$type = gettype( $theVar ) ;
switch( $type ) {
case 'array' :
$output .= $indent . $var_name . ' '.$method.' Array ('.$nl;
$keys=array_keys($theVar);
foreach($keys as $name) {
$value=&$theVar[$name];
var_log($value, $name, $reference.'["'.$name.'"]', '=', true);
}
$output .= $indent.')'.$nl;
break ;
case 'object' :
$output .= $indent.$var_name.' = '.get_class($theVar).' {'.$nl;
foreach($theVar as $name=>$value) {
var_log($value, $name, $reference.'->'.$name, '->', true);
}
$output .= $indent.'}'.$nl;
break ;
case 'string' :
$output .= $indent . $var_name . ' '.$method.' "'.$theVar.'"'.$nl;
break ;
default :
$output .= $indent . $var_name . ' '.$method.' ('.$type.') '.$theVar.$nl;
break ;
}
// $var=$var[$block];
}
-- $depth ;
if( $sub == false )
return $output ;
}
// var_log( $var, '$name' ) ;
?>
Hope it works well for you!
david at exposito dot mobi ¶
12 years ago
If you want to save exactly the content of an array into a variable to save ir later for example, use this:
<?php $xml = var_export($xml, true); ?>
You'll have in your same variable the content readable, instead of written down or anything else
divinity76 at gmail dot com ¶
11 years ago
a html-encoded var_dump
<?php
function htmlvardump(){ob_start(); $var = func_get_args(); call_user_func_array('var_dump', $var); echo htmentities(ob_get_clean());}
?>
(creds: ekneuss / mOo @ irc.freenode.net/#php )
vladimir at pixeltomorrow dot com ¶
14 years ago
You can also use the PEAR package available at http://pear.php.net/package/Var_Dump
which parses the variable content in a very pleasant manner, a lot more easier to "follow" than the built-in var_dump() function.
Of course there are many others, but I prefer this one, because it's simply to use.
Just add at the begining of your file:
<?php
require('Var_Dump.php'); // make sure the pear package path is set in php.ini
Var_Dump::displayInit(array('display_mode' => 'HTML4_Text'), array('mode' => 'normal','offset' => 4));
?>
then, instead of simply using var_dump($foo), use:
<?php
Var_Dump::display($foo);
?>
Read the documentation if you're looking for different output layouts.
Cheers!
Vladimir Ghetau
highstrike at gmail dot com ¶
14 years ago
made 2 nifty functions based of what some people contributed here. Hope you find them usefull
usage ... call for the dump function. EG: dump($array, "Array dump");
<?php
////////////////////////////////////////////////////////
// Function: dump
// Inspired from: PHP.net Contributions
// Description: Helps with php debugging
function dump(&$var, $info = FALSE)
{
$scope = false;
$prefix = 'unique';
$suffix = 'value';
if($scope) $vals = $scope;
else $vals = $GLOBALS;
$old = $var;
$var = $new = $prefix.rand().$suffix; $vname = FALSE;
foreach($vals as $key => $val) if($val === $new) $vname = $key;
$var = $old;
echo "<pre style='margin: 0px 0px 10px 0px; display: block; background: white; color: black; font-family: Verdana; border: 1px solid #cccccc; padding: 5px; font-size: 10px; line-height: 13px;'>";
if($info != FALSE) echo "<b style='color: red;'>$info:</b><br>";
do_dump($var, '$'.$vname);
echo "</pre>";
}
////////////////////////////////////////////////////////
// Function: do_dump
// Inspired from: PHP.net Contributions
// Description: Better GI than print_r or var_dump
function do_dump(&$var, $var_name = NULL, $indent = NULL, $reference = NULL)
{
$do_dump_indent = "<span style='color:#eeeeee;'>|</span> ";
$reference = $reference.$var_name;
$keyvar = 'the_do_dump_recursion_protection_scheme'; $keyname = 'referenced_object_name';
if (is_array($var) && isset($var[$keyvar]))
{
$real_var = &$var[$keyvar];
$real_name = &$var[$keyname];
$type = ucfirst(gettype($real_var));
echo "$indent$var_name <span style='color:#a2a2a2'>$type</span> = <span style='color:#e87800;'>&$real_name</span><br>";
}
else
{
$var = array($keyvar => $var, $keyname => $reference);
$avar = &$var[$keyvar];
$type = ucfirst(gettype($avar));
if($type == "String") $type_color = "<span style='color:green'>";
elseif($type == "Integer") $type_color = "<span style='color:red'>";
elseif($type == "Double"){ $type_color = "<span style='color:#0099c5'>"; $type = "Float"; }
elseif($type == "Boolean") $type_color = "<span style='color:#92008d'>";
elseif($type == "NULL") $type_color = "<span style='color:black'>";
if(is_array($avar))
{
$count = count($avar);
echo "$indent" . ($var_name ? "$var_name => ":"") . "<span style='color:#a2a2a2'>$type ($count)</span><br>$indent(<br>";
$keys = array_keys($avar);
foreach($keys as $name)
{
$value = &$avar[$name];
do_dump($value, "['$name']", $indent.$do_dump_indent, $reference);
}
echo "$indent)<br>";
}
elseif(is_object($avar))
{
echo "$indent$var_name <span style='color:#a2a2a2'>$type</span><br>$indent(<br>";
foreach($avar as $name=>$value) do_dump($value, "$name", $indent.$do_dump_indent, $reference);
echo "$indent)<br>";
}
elseif(is_int($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color$avar</span><br>";
elseif(is_string($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color\"$avar\"</span><br>";
elseif(is_float($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color$avar</span><br>";
elseif(is_bool($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color".($avar == 1 ? "TRUE":"FALSE")."</span><br>";
elseif(is_null($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> {$type_color}NULL</span><br>";
else echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $avar<br>";
$var = $var[$keyvar];
}
}
?>
fabien dot villepinte at gmail dot com ¶
3 years ago
It's important to note that the output depends on the precision directive.
<?php
var_dump(10000000000000.5); // float(10000000000000)
ini_set('precision',-1);
var_dump(10000000000000.5); // float(10000000000000.5)
?>
jonbarnett at gmail dot com ¶
15 years ago
dumping objects that reference each other could lead to infinite recursion
<?php
$brother = new Sibling();
$sister = new Sibling();
$brother->sister = $sister;
$sister->brother = $brother;
var_dump($brother);
/* dumps all of $brother's properties, including "sister", which dumps all of $sister's properties, including "brother", etc. */
?>
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