PHP: Post validate

post_validate.php

foreach($_POST as $key => $value){
			
	switch($key){
					
		case $key == 'email':
			if ($value == ''){
				$data['error'][] = array($key,'Enter your email');
			}
			else{
				if (!filter_var($value, FILTER_VALIDATE_EMAIL)){
					$data['error'][] = array($key,'Enter a valid email');
				}
			}
		break;
		
		case $key == 'password':
			if ($value == ''){
				$data['error'][]= array($key,'Enter a password');
			}
		break;
					
	}
	
}
		
if(!array_key_exists('error',$data)){

}