PHP: print_r - Manual

Description

bool print_r ( mixed expression [, bool return] )

Note: 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() and var_export() will also show protected and private properties of objects with PHP 5, on the contrary to var_dump().

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>

The above example will output:

<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).

Example 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 ?>

Note: 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.

Note: 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.

User Contributed Notes
print_r

james at jyopp <dotcom>
04-May-2005 01:56


Here's a simpler way to use print_r to get readable output to the browser:



<?php

   print "<pre>".print_r($var, true)."</pre>";

?>



It's clean, fast, and hasn't had any problems for me so far...

cmadole [at] jamspiritsites [dot] com
18-Mar-2005 03:06


I've found this to be handy adaptation of print_r for outputing arrays to a browser; it saves you from having to look at the source code.



<?php

function html_print_r($object, $returnValue = false) {

    $output = print_r($object, true);

    $output = htmlentities($output);

    $output = str_replace(" ", "&nbsp;", );

    $output = nl2br($output);



    if ($returnValue) {

        return $output;

    } else {

        echo $output;

        return true;

    }

}

?>

general at bugfoo dot com
20-Jan-2005 08:56


Correction to below: you can't use them in a function which is a callback of ob_start().

general at NOSPAMbugfoo dot com
20-Jan-2005 03:23


You can't use print_r($var, TRUE) if you are already buffering or inside a function which is buffering or you get the following error:

Fatal error: print_r(): Cannot use output buffering in output buffering display handlers

peranders at peranders dot net
26-Oct-2004 10:13


These functions will print human-readable information

about a variable in HTML format

Only tested in PHP Version 4.3.1

<?

$person=new stdClass();

$person->name="Jonny";

$person->interests=array('Fishing','Hiking');



echo "<H1>marr (PHP 4 , PHP 5) </H1>";

marr($person);

echo "<H1>marr for all versions 4.3.x above</H1>";

marr_php_version_4_3($person);



function marr($a)

{

    ob_start();

    print_r($a);

    $t= ob_get_contents();

    ob_end_clean();

    for($c=10;$c>=1;$c--)

    {

        $search="\n ".str_repeat(" ",4*$c-1);

        $replace="<br>\n".str_repeat("&nbsp;",8*$c);

        $t= str_replace($search,$replace,$t);

    }

    //Final adjustment which takes care of the single last closing parenthesis 

    $t= str_replace("\n\n)","<br>\n)",$t);



    echo $t;

}



function marr_php_version_4_3($a)

{

    $t=print_r($a,true);

    for($c=10;$c>0;$c--)

    {

        $search="\n ".str_repeat(" ",4*$c-1);

        $replace="<br>\n".str_repeat("&nbsp;",8*$c);

        $t= str_replace($search,$replace,$t);

    }

    //Final adjustment which takes care of the single last closing parenthesis 

    $t= str_replace("\n\n)","<br>\n)",$t);

    echo $t;

}

?>