Function handling 함수 목록
PHP Manual

function_exists

(PHP 4, PHP 5)

function_existsReturn TRUE if the given function has been defined

설명

bool function_exists ( string $function_name )

Checks the list of defined functions, both built-in (internal) and user-defined, for function_name .

인수

function_name

The function name, as a string.

반환값

Returns TRUE if function_name exists and is a function, FALSE otherwise.

Note: This function will return FALSE for constructs, such as include_once() and echo().

예제

Example #1 function_exists() example

<?php
if (function_exists('imap_open')) {
    echo 
"IMAP functions are available.<br />\n";
} else {
    echo 
"IMAP functions are not available.<br />\n";
}
?>

주의

Note: A function name may exist even if the function itself is unusable due to configuration or compiling options (with the image functions being an example).

참고


Function handling 함수 목록
PHP Manual