PHP Manual: Prints human-readable information about a variable

Description

mixed print_r ( mixed $expression [, bool $return = false ] )

print_r displays information about a variable in a way that's readable by humans.

print_r, var_dump and var_export will also show protected and private properties of objects with PHP 5. Static class members will not be shown.

Parameters

expression: The expression to be printed.
return: If you would like to capture the output of print_r, use the return parameter. When this parameter is set to TRUE, print_r will return the information rather than print it.

Return Values

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.

When the return parameter is TRUE, this function will return a string. Otherwise, the return value is TRUE.

Notes

Note:
When the return parameter is used, this function uses internal output buffering so it cannot be used inside an ob_start callback function.

Changelog

Version	Description
4.3.0	The `return` parameter was added. If you need to capture the output of print_r with an older version of PHP prior, use the output-control functions.
4.0.4	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.

Examples

Example #1 print_r example


<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>

Example #2 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
?>

print_r