Try this:
if (!empty($Zip) && (strlen($Zip) !== 4)){
Apply this code and remove your code. It will work.
문제
I want to only check for length of this value if the variable is not empty and ignore checking length if the variable is empty. The following Always checks length and doesn't consider the first parameter of the if statement.
PHP
if ($Zip !== '' && (strlen($Zip) !== 4)){
해결책
Try this:
if (!empty($Zip) && (strlen($Zip) !== 4)){
Apply this code and remove your code. It will work.