Write a program in Php to check whether a number is prime or not?

The program in Php to check whether a number is prime or not is as follows :

<?php

function primeCheck($number){

    if ($number == 1)

    return 0;

    for ($i = 2; $i <= $number/2; $i++){

        if ($number % $i == 0)

            return 0;

    }

    return 1;

}

$number = 31;

$flag = primeCheck($number);

if ($flag == 1)

    echo "Prime";

else

    echo "Not Prime"

?>