Verify that the contents of a variable can be called as a function

is_bool
is_double
Variable handling Functions
PHP Manual

# is_callable

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

is_callable — Verify that the contents of a variable can be called as a function

### Description

bool is_callable ( mixed `$var` [, bool `$syntax_only` = false [, string `&$callable_name` ]] )

Verify that the contents of a variable can be called as a function. This can check that a simple variable contains the name of a valid function, or that an array contains a properly encoded object and function name.

### Parameters

`var`

  The value to check

`syntax_only`

  If set to `TRUE` the function only verifies that `name` might be a function or method. It will only reject simple variables that are not strings, or an array that does not have a valid structure to be used as a callback. The valid ones are supposed to have only 2 entries, the first of which is an object or a string, and the second a string.

`callable_name`

  Receives the "callable name". In the example below it is "someClass::someMethod". Note, however, that despite the implication that someClass::SomeMethod() is a callable static method, this is not the case.

### Return Values

Returns `TRUE` if `var` is callable, `FALSE` otherwise.

### Examples

Example #1 is_callable() example

`<?php
// How to check a variable to see if it can be called
// as a function.
//
// Simple variable containing a function
//
function someFunction()
{
}
$functionVariable = 'someFunction';
var_dump(is_callable($functionVariable, false, $callable_name)); // bool(true)
echo $callable_name, "\n"; // someFunction
//
// Array containing a method
//
class someClass {
function someMethod()
{
}
}
$anObject = new someClass();
$methodVariable = array($anObject, 'someMethod');
var_dump(is_callable($methodVariable, true, $callable_name)); // bool(true)
echo $callable_name, "\n"; // someClass::someMethod
?>`

### See Also

- function_exists() - Return TRUE if the given function has been defined
- method_exists() - Checks if the class method exists

is_bool
is_double
Variable handling Functions
PHP Manual