Question

How to find of all the prime numbers in an array with PHP

Answer 1

function isPrime($n) {
    if ($n == 0) return 0;
    if ($n == 1) return 0;
    for ($i = 2; $i <= sqrt($n); $i++) {
        if ($n % $i == 0)
            return 0;
    }
    return 1;
}


$arr = array(4, 8, 5, 17, 9, 22, 21, 13, 18, 99);

for ($i = 0; $i < sizeof($arr); $i++) {
      if (isPrime($arr[$i])) {
           echo $arr[$i] . " ";
      }
}

   
       
/*
run:
            
5 17 13 
     
*/

 

70+ SQL courses for beginners and professionals