function prime($n, $i = 2)
{
if ($n == $i) {
return 0;
} else {
if (!($n % $i)) {
return 1;
} else {
return prime($n, $i + 1);
}
}
}
function prime($number, $i)
{
if ($i == 1) {
return 1;
} else {
if ($number % $i == 0) {
return 1 + prime($number, --$i);
} else {
0 + prime($number, --$i);
}
}
}
function prime_factors_rev($num)
{
for ($i = (int) ($num / 2); $i >= 2; $i--) {
if (prime($i)) {
if ($num % $i == 0) {
return $i;
}
}
}
return $num;
}
<?php
function prime($a)
{
if ($a % 2 == 0 && $a != 2 || $a < 2) {
return false;
}
$limit = sqrt($a);
for ($i = 2; $i <= $limit; $i++) {
if ($a % $i == 0) {
return false;
}
}
return true;
}
foreach (range(1, 100) as $x) {
if (prime($x)) {
echo "{$x}\n";
}
}
<?php
/**
* prime() determines the prime number
* Use iteration method
*
* @param [integer] $input [The input number]
* @return [integer] 1 or 0 [The prime result]
*/
function prime($input)
{
for ($i = 2; $i <= ceil(sqrt($input)); $i++) {
if ($input % $i == 0) {
return 1;
}
}
return 0;
}
$number = 13;
if (prime($number) == 1) {
echo "{$number} is not a prime number";
} else {
echo "{$number} is a prime number";
}
echo '<br><br>';
function sum($a, $b)
{
$c = $a + $b;
return $c;
}
$sum2 = sum(6, 34);
echo 'sum of two digit = ' . $sum2;
echo '<br><br>';
function prime($j)
{
for ($l = 2; $l < $j; $l++) {
if ($j % $l == 0) {
$m = 0;
break;
} else {
$m = 1;
}
}
return $m;
}
$prime2 = prime(59);
if ($prime2 == 1) {
echo 'this is prime no.';
} else {
echo 'this is not a prime number';
}
echo '<br><br>';
?>
</body>
</html>
//numbers to be checked as prime
$counter = 0;
for ($j = 1; $j <= $i; $j++) {
//all divisible factors
if ($i % $j == 0) {
$counter++;
}
}
//prime requires 2 rules ( divisible by 1 and divisible by itself)
if ($counter == 2) {
print $i . "<br/>";
}
}
}
echo '<strong>Prime Number 2,3,5,7....</strong></br>';
prime(20);
//find prime numbers from 1-20
echo str_repeat('-', 100) . '</br>';
/*********************************************************************************
************************ Star Triangle ******************************************
********************************************************************************/
echo '<strong>Star Triangle</strong></br>';
for ($i = 0; $i <= 5; $i++) {
for ($j = 1; $j <= $i; $j++) {
echo "* ";
}
echo "<br>";
}
echo "<br>";
/********************************************************************************/
for ($i = 0; $i <= 5; $i++) {
<?php
error_reporting(-1);
$min = 1;
$max = 100;
$total = 0;
$message = $min . "~" . $max . "までの素数を除いた数字を足す";
if (isset($_POST['add'])) {
// $min~$maxまでの足し算を繰り返す
for ($i = $min; $i <= $max; $i++) {
$count = 0;
prime($i, $count);
$total = $total + $i;
}
$message = $min . "~" . $max . "までの素数を除いた合計は" . $total . "です。";
}
// 素数を判定して飛ばす関数
function prime(&$i, &$count)
{
// 1から$iまでの数で$1を剰余算
for ($j = 1; $j <= $i; $j++) {
// わり切れた回数をカウント
if ($i % $j == 0) {
$count = $count + 1;
}
}
// わり切れた回数が二回なら素数
if ($count == 2) {
// 2は次が素数なので二つ飛ばす
if ($i == 2) {
$i = $i + 2;
/**
* @depends testPrimeLoader
*/
public function testPrime()
{
$this->assertEquals(2, prime(1), '1st prime number');
$this->assertEquals(29, prime(10), '10th prime number');
$this->assertEquals(7919, prime(1000), '1000th prime number');
}