PHP method to determine whether an array is a subset of another array

// Quickly determine whether $a array is a subset of $b array
$a = array(135,138);
$b = array(135,138,137);

implementation method: Method 1, for loop traversal

$flag = 1;
foreach ($a as $va) {
 if (in_array($va, $b)) {
 continue;
 }else {
 $flag = 0;
 break;
 }
}

if ($flag) {
 echo "Yes";
}else {
 echo "No";
}

Method 2, use of PHP method to determine whether an array is a subset of another array

Code:

$c = PHP method to determine whether an array is a subset of another array($a, $b);
print_r($c);
$flag = empty($c)?1 : 0;

if ($flag ) {
 echo "Yes";
}else {
 echo "No";
}

Method 3, use of PHP method to determine whether an array is a subset of another array

Example:

if ($a == PHP method to determine whether an array is a subset of another array($a, $b)) {
 $flag = 1;
}else {
 $flag = 0;
}

if ($ flag) {
 echo "Yes";
}else {
 echo "No";
}