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PHParadise > html and code > prime numbers

function to check wether a number is a prime number or not.
returns TRUE if number given is a prime number and FALSE if not.

copy the code of html and code / prime numbers

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<?php

/*------------------------------------------------------------------------------
|
|                             PHParadise source code
|
|-------------------------------------------------------------------------------
|
| file:             prime numbers
| category:         html and code
|
| last modified:    Tue, 21 Jun 2005 01:06:05 GMT
| downloaded:       Wed, 08 Sep 2010 01:21:16 GMT as copy from textarea
|
| code URL:
| http://phparadise.de/php-code/html-and-code/prime-numbers/
|
| description:
| function to check wether a number is a prime number or not. returns TRUE if
| number given is a prime number and FALSE if not.
|
------------------------------------------------------------------------------*/

// is_prime(number) checks if a number is a prime number or not
function is_prime($i)
{
	if($i % 2 != 1) return false;
	$d = 3;
	$x = sqrt($i);
	while ($i % $d != 0 && $d < $x) $d += 2;
	return (($i % $d == 0 && $i != $d) * 1) == 0 ? true : false;
}

// example: show all prime numbers between $start and $end

$start = 0;
$end = 1000;

echo '
<p>
	all prime numbers between '.$start.' and '.$end.'
</p>
<p>';

for($i = $start; $i <= $end; $i++)
{
	if(is_prime($i))
	{
		echo '
'.$i.' ';
	}
}

echo '
</p>';

PHParadise source code of “prime numbers” in category “html and code”

PHParadise > html and code > prime numbers

copy the code of html and code / prime numbers