Question

How to calculate the Nth prime number in PHP

Answer 1

// 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73

function GetTheNthPrimeNumber($nth) {
    $prime = 1;
    $count = 0;

    while ($count < $nth) {
        $prime += 1;
        for ($i = 2; $i <= $prime; $i++) {
            if ($prime % $i == 0) {
                break;
            }
        }
        if ($i == $prime) {
            $count += 1;
        }
    }

    return $prime;
}

$nth = 8;

echo "Nth prime: " . GetTheNthPrimeNumber($nth);


  
/*
run:
   
1 
2 3 
4 5 6 
7 8 9 10 
11 12 13 14 15 
16 17 18 19 20 21 
22 23 24 25 26 27 28 
    
*/

 

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