[php] if(empty($outsourcing)) 이 조건문은 null 이나 '' 전부 잡아내나?empty에 대해 알아보자구요.

empty 함수는 PHP에서 다음과 같은 값을 비어 있다고 판단합니다:

"" (빈 문자열)
0 (정수 0)
"0" (문자열 0)
NULL
FALSE
array() (빈 배열)
var $var; (정의는 되었으나 값이 없는 변수)
따라서 empty($outsourcing) 조건문은 $outsourcing 변수가 null, 빈 문자열, 숫자 0, 문자열 "0", false, 빈 배열 등일 때 모두 true를 반환합니다.

좀 더 구체적으로 확인하고 싶다면 is_null 또는 trim과 함께 조건을 사용하는 방법도 있습니다:

if (is_null($outsourcing) || $outsourcing === '') {
    // null 또는 빈 문자열인 경우
}
또는

if (empty($outsourcing)) {
    // $outsourcing이 비어 있는 경우 (위의 모든 경우 포함)
}
이렇게 하면 특정 조건에 대해서만 검출할 수 있습니다.

$outsourcing1 = null;
$outsourcing2 = '';
$outsourcing3 = '0';
$outsourcing4 = 0;
$outsourcing5 = false;
$outsourcing6 = array();
$outsourcing7 = 'some value';

var_dump(empty($outsourcing1)); // true
var_dump(empty($outsourcing2)); // true
var_dump(empty($outsourcing3)); // true
var_dump(empty($outsourcing4)); // true
var_dump(empty($outsourcing5)); // true
var_dump(empty($outsourcing6)); // true
var_dump(empty($outsourcing7)); // false
empty 함수는 넓은 범위의 "비어 있는" 값을 포괄하기 때문에 매우 유용하지만, 특정한 비어 있음 조건만을 검출하려는 경우에는 주의가 필요합니다.

$outsourcing1 = null;
$outsourcing2 = '';
$outsourcing3 = '0';
$outsourcing4 = 0;
$outsourcing5 = false;
$outsourcing6 = array();
$outsourcing7 = 'some value';

var_dump(empty($outsourcing1)); // true
var_dump(empty($outsourcing2)); // true
var_dump(empty($outsourcing3)); // true
var_dump(empty($outsourcing4)); // true
var_dump(empty($outsourcing5)); // true
var_dump(empty($outsourcing6)); // true
var_dump(empty($outsourcing7)); // false