w3resource

PHP: is_callable() function

Description

The is_callable() function is used to test that the contents of a variable, whether it can be called as a function or not.

Version:

(PHP 4 and above)

Syntax:

is_callable(var_name, syntax_only, callable_name)

Parameters:

Name Description Required /
Optional
Type
var_name Either the name of a function stored in a string variable, or an object and the name of a method within the object. Required Mixed*
syntax_only If set to TRUE, the function only verifies if it is a function or a method. It rejects simple variables those are not strings and an array not having a valid structure. Optional Boolean
callable_name Receives a "callable name". This option is implemented only for classes. Optional String

*Mixed : Mixed indicates that a parameter may accept multiple (but not necessarily all) types.

Return value:

TRUE if var_name is callable, FALSE otherwise.

Value Type: Boolean.

Example :

<?php
function foo(){
}
echo is_callable('foo');
echo is_callable('bar');
?>

Output :

1

View the example in the browser

Practice here online :

See also

PHP Function Reference

Previous: is_bool
Next: is_double



PHP: Tips of the Day

PHP - how to create a newline character?

Only double quoted strings interpret the escape sequences \r and \n as '0x0D' and '0x0A' respectively, so you want:

"\r\n"

Single quoted strings, on the other hand, only know the escape sequences \\ and \'.

So unless you concatenate the single quoted string with a line break generated elsewhere (e. g., using double quoted string "\r\n" or using chr function chr(0x0D).chr(0x0A)), the only other way to have a line break within a single quoted string is to literally type it with your editor:

$s = 'some text before the line break
some text after';

Make sure to check your editor for its line break settings if you require some specific character sequence (\r\n for example).

Ref : https://bit.ly/3hcyege