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Description

bool print_r ( mixed expression [, bool return] )

Замечание: The return parameter was added in PHP 4.3.0

print_r() displays information about a variable in a way that's readable by humans. If given a string, integer or float, the value itself will be printed. If given an array, values will be presented in a format that shows keys and elements. Similar notation is used for objects. print_r(), var_dump() and var_export() will also show protected and private properties of objects with PHP 5.

Remember that print_r() will move the array pointer to the end. Use reset() to bring it back to beginning.


<pre>

<?php

    $a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x', 'y', 'z'));

    print_r ($a);

?>

</pre>

Результат выполнения данного примера:

<pre>
Array
(
    [a] => apple
    [b] => banana
    [c] => Array
        (
            [0] => x
            [1] => y
            [2] => z
        )
)
</pre>

If you would like to capture the output of print_r(), use the return parameter. If this parameter is set to TRUE, print_r() will return its output, instead of printing it (which it does by default).

Замечание: This function internally uses the output buffering with this parameter so it can not be used inside ob_start() callback function.

Пример 1. return parameter example

<?php $b = array ('m' => 'monkey', 'foo' => 'bar', 'x' => array ('x', 'y', 'z')); $results = print_r($b, true); //$results now contains output from print_r ?>

Замечание: If you need to capture the output of print_r() with a version of PHP prior to 4.3.0, use the output-control functions.

Замечание: Prior to PHP 4.0.4, print_r() will continue forever if given an array or object that contains a direct or indirect reference to itself. An example is print_r($GLOBALS) because $GLOBALS is itself a global variable that contains a reference to itself.

add a note User Contributed Notes
print_r

bart at mediawave dot nl
30-Oct-2007 05:27


Here's a PHP version of print_r which can be tailored to your needs. Shows protected and private properties of objects and detects recursion (for objects only!). Usage:



void u_print_r ( mixed $expression [, array $ignore] )



Use the $ignore parameter to provide an array of property names that shouldn't be followed recursively.



<?php



function u_print_r($subject, $ignore = array(), $depth = 1, $refChain = array()) 

{

    if ($depth > 20) return;

    if (is_object($subject)) {

        foreach ($refChain as $refVal)

            if ($refVal === $subject) {

                echo "*RECURSION*\n";

                return;

            }

        array_push($refChain, $subject);

        echo get_class($subject) . " Object ( \n";

        $subject = (array) $subject;

        foreach ($subject as $key => $val)

            if (is_array($ignore) && !in_array($key, $ignore, 1)) {

                echo str_repeat(" ", $depth * 4) . '[';

                if ($key{0} == "\0") {

                    $keyParts = explode("\0", $key);

                    echo $keyParts[2] . (($keyParts[1] == '*')  ? ':protected' : ':private');

                } else

                    echo $key;

                echo '] => ';

                u_print_r($val, $ignore, $depth + 1, $refChain);

            }

        echo str_repeat(" ", ($depth - 1) * 4) . ")\n";

        array_pop($refChain);

    } elseif (is_array($subject)) {

        echo "Array ( \n";

        foreach ($subject as $key => $val)

            if (is_array($ignore) && !in_array($key, $ignore, 1)) {

                echo str_repeat(" ", $depth * 4) . '[' . $key . '] => ';

                u_print_r($val, $ignore, $depth + 1, $refChain);

            }

        echo str_repeat(" ", ($depth - 1) * 4) . ")\n";

    } else

        echo $subject . "\n";

}



?>



Example:



<?php



class test {



    public $var1 = 'a';

    protected $var2 = 'b';

    private $var3 = 'c';

    protected $array = array('x', 'y', 'z');



}



$test = new test();

$test->recursiveRef = $test;

$test->anotherRecursiveRef->recursiveRef = $test;

$test->dont->follow = 'me';



u_print_r($test, array('dont'));



?>



Will produce:



test Object ( 

    [var1] => a

    [var2:protected] => b

    [var3:private] => c

    [array:protected] => Array ( 

        [0] => x

        [1] => y

        [2] => z

    )

    [recursiveRef] => *RECURSION*

    [anotherRecursiveRef] => stdClass Object ( 

        [recursiveRef] => *RECURSION*

    )

)

php at deboom dot biz
21-Sep-2007 05:17


If you need to import an print_R output back to an array you could use this.



This could also be (ab)used to convert a object into a array...



<?php

function object2array($printr) {                    

        $newarray = array();        

        $a[0] = &$newarray;        

        if (preg_match_all('/^\s+\[(\w+).*\] => (.*)\n/m', $printr, $match)) {                        

            foreach ($match[0] as $key => $value) {    

                (int)$tabs = substr_count(substr($value, 0, strpos($value, "[")), "        ");                

                if ($match[2][$key] == 'Array' || substr($match[2][$key], -6) == 'Object') {                    

                    $a[$tabs+1] = &$a[$tabs][$match[1][$key]];

                }                            

                else {

                    $a[$tabs][$match[1][$key]] = $match[2][$key];                    

                }

            }

        }    

        return $newarray;    

    }

?>

motin at demomusic dot nu
19-Jun-2007 04:01


This works around the hacky nature of print_r in return mode (using output buffering for the return mode to work is hacky...):



<?php

/**

  * An alternative to print_r that unlike the original does not use output buffering with

  * the return parameter set to true. Thus, Fatal errors that would be the result of print_r

  * in return-mode within ob handlers can be avoided.

  *

  * Comes with an extra parameter to be able to generate html code. If you need a

  * human readable DHTML-based print_r alternative, see http://krumo.sourceforge.net/

  *

  * Support for printing of objects as well as the $return parameter functionality

  * added by Fredrik Wolls