PHP: Prints human-readable information about a variable

Description

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

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.

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

Parameters

expression: The expression to be printed.
return: 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).

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.

Notes

Note: This function uses internal output buffering with this parameter so it can not 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