PHP - check if number is prime

Question

I\'m trying to create a function which checks whether the number is prime or not. BUT I want this function to echo to the user \'prime\' or \'NOT prime\' - and that\'s where my

Answer 1

$num = ceil(sqrt($num));

$is_prime = true;
for($j=3; $j<=$num; $j=$j+2){
    if($i%$j == 0){         
        $is_prime = false;
        break;
    }
}

if($is_prime){
    echo "No is Prime";
}

Note: Start loop from 2 as it is the only even prime no. Increment with 2 as no even no is a prime no.

=> Code for finding all prime no in range (2-100)

$limit = 100; $arr = array(2);
for($i=3; $i<=$limit; $i=$i+2){

    $num = ceil(sqrt($i));

    $is_prime = true;
    for($j=3; $j<=$num; $j=$j+2){
        if($i%$j == 0){         
            $is_prime = false;
            break;
        }
    }

    if($is_prime){
        $arr[] = $i;
    }
}