Prime Number Program
How To Check Prime Number Using PHP
A number which is only divisible by 1 and itself is called a prime number. Numbers 2, 3, 5, 7, 11, 13, 17, etc. are prime numbers.
- 2 is the only even prime number.
- It is a natural number greater than 1 and so 0 and 1 are not prime numbers.
Prime number program using PHP
Example:
Write a program to check the first 15 prime numbers.
<?php
$count = 0;
$num = 2;
while ($count < 15 )
{
$div_count=0;
for ( $i=1; $i<=$num; $i++)
{
if (($num%$i)==0)
{
$div_count++;
}
}
if ($div_count<3)
{
echo $num." , ";
$count=$count+1;
}
$num=$num+1;
}
?>
Output: 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47
Prime Number using Form in PHP
Example:
We'll show a form, which will check whether a number is prime or not.
<form 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";
}
}
?>
Output:
On entering number 12, we get the following output. It states that 12 is not a prime number.
The Number 12 is not prime
Check 2: check number is a prime or not
On entering number 97, we get the following output. It states that 97 is a prime number.
The Number 97 is prime
Series:
PHP Tutorials Hub
