How To Check a Prime Number in PHP Example Tutorial

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Inside this article we will see the concept i.e How To Check a Prime Number in PHP Tutorial. Article contains the classified information about a program which checks a number is prime or not using PHP.

If you are looking for a solution to a PHP Program To Check Whether a Number is Prime or Not then this article will help you a lot for this. Tutorial is super easy to understand and implement it in your code as well.

What is a Prime Number?

A prime number is a whole number greater than 1 whose only factors are 1 and itself. A factor is a whole number that can be divided evenly into another number. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29.

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Let’s get started.

Example: Using PHP To Check Prime Numbers


We will use the concept of PHP i.e How To Check a Prime Number in PHP.

Create a file with name index.php inside your localhost directory. Open file and write this code into it.


function IsPrimeOrNot($n)
   for($i=2; $i<$n; $i++) {
      if ($n % $i ==0) {
           return 0;

   return 1;

$result = IsPrimeOrNot(5);

if ($result==0){
  echo 'This is not a Prime Number.';
  echo 'This is a Prime Number.';


This is a Prime Number.

Example: Check Prime Number in PHP using a Form

Here we will create a PHP program with PHP Forms for how to check a whether a given number is prime or not.


   <title>Prime Number using Form in PHP</title>

   <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
      Enter a Number: <input type="text" name="input"><br><br>
      <input type="submit" name="submit" value="Submit">
   if ($_POST) {
      $input = $_POST['input'];
      for ($i = 2; $i <= $input - 1; $i++) {
         if ($input % $i == 0) {
            $value = True;
      if (isset($value) && $value) {
         echo 'The Number ' . $input . ' is not prime';
      } else {
         echo 'The Number ' . $input . ' is prime';



We entered a value 5 into input and submit:

Example: Get Prime Numbers Between 1 and 100


We have created a function checkPrime() to check whether the number is prime or not.

We loop over the number range (1 to 100) and pass each as a parameter to the function to check whether a number is prime or not.


function checkPrime($num)
   if ($num == 1)
      return 0;
   for ($i = 2; $i <= $num / 2; $i++) {
      if ($num % $i == 0)
         return 0;
   return 1;

echo '<h2>Prime Numbers between 1 and 100</h2> ';

for ($num = 1; $num <= 100; $num++) {

   $flag = checkPrime($num);

   if ($flag == 1) {
      echo $num . " ";


We hope this article helped you to learn How To Check a Prime Number in PHP Example Tutorial in a very detailed way.

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Sanjay KumarHello friends, I am Sanjay Kumar a Web Developer by profession. Additionally I'm also a Blogger, Youtuber by Passion. I founded Online Web Tutor and Skillshike platforms. By using these platforms I am sharing the valuable knowledge of Programming, Tips and Tricks, Programming Standards and more what I have with you all. Read more