var_dump

(PHP 4, PHP 5, PHP 7, PHP 8)

var_dump — Виводить інформацію про змінну

Опис

var_dump(mixed $expression, mixed $... = ?): void

Ця функція виводить структуровану інформацію про один чи кілька виразів, включаючи значення й тип цього значення. Масиви і об'єкти відображаються рекурсивно та з відступами, при показі їх вкладених структур.

Всі публічні, захищені та приватні властивості об'єктів будуть повертатись для виводу, окрім об'єктів, де впроваджено метод __debugInfo() (який з'явився в PHP 5.6.0).

Підказка

Як і для будь-чого, що виводить свій результат прямо в браузер, можна використовувати функції контролю виводу для перехоплення виводу даних цією функцією, та збереження їх, наприклад, у вигляді рядка (string).

Параметри

expression: Вираз, про який потрібно виводити інформацію.

Значення, що повертаються

Не повертає значень.

Приклади

Приклад #1 Використання var_dump()

<?php
$a = array(1, 2, array("a", "b", "c"));
var_dump($a);
?>

Поданий вище приклад виведе:

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);

?>

Поданий вище приклад виведе:

float(3.1)
bool(true)

Прогляньте також

print_r() - Prints human-readable information about a variable
debug_zval_dump() - Dumps a string representation of an internal zval structure to output
var_export() - Outputs or returns a parsable string representation of a variable
__debugInfo()

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User Contributed Notes 16 notes

down

133

edwardzyang at thewritingpot dot com ¶

19 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).

down

148

rich dot schu at gmail dot com ¶

16 years ago

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

down

b dot bergloev at gmail dot com ¶

10 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") . ";\">&nbsp;&#10549;</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>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
                    }

                    echo $isTerminal ? "\n" : "<br />";
                }

                for ($i=0; $i <= $level; $i++) {
                    echo $isTerminal ? "|    " : "<span style='color:black'>|</span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
                }

                echo $isTerminal ? "[" . $key . "] => " : "<span style='color:black'>[" . $key . "]&nbsp;=>&nbsp;</span>";

                call_user_func($recursive, $value, $level+1);
            }

            if ($notEmpty) {
                for ($i=0; $i <= $level; $i++) {
                    echo $isTerminal ? "|    " : "<span style='color:black'>|</span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
                }

                if (!$isTerminal) {
                    echo "</div>";
                }

            } else {
                echo $isTerminal ? 
                        $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "  " : 
                        "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span>&nbsp;&nbsp;";
            }

        } else {
            echo $isTerminal ? 
                    $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "  " : 
                    "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span>&nbsp;&nbsp;";

            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);
}
?>

down

anon ¶

19 years ago

var_dump(get_defined_vars());
will dump all defined variables to the browser.

down

thriller dot ze at gmail dot com ¶

17 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>';
?>

down

stlawson *AT* joyfulearthtech *DOT* com ¶

13 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> &nbsp;&nbsp; ";
    $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'>$type</span> = <span style='color:#e87800;'>&amp;$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>";
}
?>

down

highstrike at gmail dot com ¶

16 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> &nbsp;&nbsp; ";
    $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'>$type</span> = <span style='color:#e87800;'>&amp;$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];
    }
}
?>

down

Anonymous ¶

8 years ago

Be careful this outputs to stdout stream (1) instead of the proper stderr stream (2).

down

php at mikeboers dot com ¶

17 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!

down

kobrasrealm at gmail dot com ¶

13 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.

down

egorinsk at gmail com ¶

15 years ago

Note that var_dump reset()'s array internal pointer!

down

david at exposito dot mobi ¶

14 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

down

vladimir at pixeltomorrow dot com ¶

17 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

down

-3

divinity76 at gmail dot com ¶

13 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 )

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-2

fabien dot villepinte at gmail dot com ¶

5 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)
?>

down

-4

jonbarnett at gmail dot com ¶

18 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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