Test if one array is a subset of another

Question

How can I determine if one array is a subset of another (all elements in the first are present in the second)?

 $s1 = \"string1>string2>string3>string4&         


        

Answer 1

$s1 = "1>2>3>4>5>6>7";

$arr1 = explode(">",$s1);

$s2 = "1>2>3";

$arr2 = explode(">",$s2); 

if(isSub($arr1,$arr2)){

         echo 'true';

}else{

         echo 'false';
}

function isSub($a1,$a2){

    $num2 = count($a2);
    $sub  = $num2;

    for($i = 0;$i < $num2 ;$i++){
        if(in_array($a2[$i],$a1)){
            $sub--;
        }
    }
    return ($sub==0)? true:false;
}