# 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.

Learn More –

Let’s get started.

## Example: Using PHP To Check Prime Numbers

Here,

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.

```<?php

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.';
}else{

echo 'This is a Prime Number.';
}
```

Output

``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.

```<html>

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

<body>
<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">
</form>
<?php
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';
}
}
?>
</body>

</html>
```

Outputb

We entered a value 5 into input and submit:

## Example: Get Prime Numbers Between 1 and 100

Here,

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.

```<?php

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 . " ";
}
}
```

Output

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