php 한글 메뉴얼 도움말 검색 사이트 Checks whether a given named constant exists [function.defined]

설명

bool defined ( string $name )

Checks whether the given constant exists and is defined.

Note:
If you want to see if a variable exists, use isset() as defined() only applies to constants. If you want to see if a function exists, use function_exists().

인수

name: The constant name.

반환값

Returns TRUE if the named constant given by name has been defined, FALSE otherwise.

예제

Example #1 Checking Constants


<?php
/* Note the use of quotes, this is important.  This example is checking
 * if the string 'TEST' is the name of a constant named TEST */
if (defined('TEST')) {
    echo TEST;
}
?>

참고

define() - Defines a named constant
constant() - 상수 값을 반환합니다
get_defined_constants() - 모든 상수와 그 값의 연관 배열을 반환합니다
function_exists() - Return TRUE if the given function has been defined
The section on Constants