call_user_func

Synopsis

Returns

The return value of function_name; if function_name is not a valid function name, the function generates a warning and no value is returned

Description

call_user_func() is primarily useful as a way to dynamically call functions and methods at runtime without having to use eval() .

Normally, functions are called with the following syntax:

function_name ('arg one', 'arg two', ...);

Calling the same function using call_user_func() would look like this:

call_user_func ('function_name', 'arg one', 'arg two', ...);

The function name is somewhat of a misnomer - any PHP function can be called using this function. Watch out for language constructs like print() , echo() , unset() , etc. Attempts to call these constructs using this function will generate a warning.

$result = call_user_func (array (&$object, 'method'), $arg1, $arg2, ...);

Version

PHP Version: 3.0.3+, 4+

See also

To call an object method in the same manner:

call_user_method()

To pass a variable number of arguments to a function (or method):

call_user_func_array()

func_get_arg()

func_get_args()

func_num_args()

Example

<pre>
<?php
$function_name = 'printf';
$format_string = "%-'.45s$%0.2f\n";

// Call printf using call_user_func
call_user_func ($function_name, $format_string, "Total Cost", 1.1);

// Make the same call to printf in the standard fashion
printf ($format_string, "Total Cost", 1.1);

// Make the same call to printf using the variable function behavior
$function_name ($format_string, "Total Cost", 1.1);
?>
</pre>