Determine whether it is a prime number. A prime number refers to a natural number that has no other factors except 1 and itself among natural numbers greater than 1. (Recommended learning: PHP video tutorial)
<html>
<?php
if (!empty($_POST)) {
$num = $_POST["num"];
$count = 0;
for ($i = 1; $i <= $num; ++$i) {
if ($num % $i == 0) {
$count++;
}
}
} else {
$num = "";
$count = "";
}
?>
<form action="" method="post">
<input type="text" name="num" value="<?php
echo $num;
?>"/>
<input type="button" name="tip" value="<?php
if ($count == 2) {
echo $num . "是素数";
} else {
echo $num . "不是素数";
}
?>"/>
<input type="submit" value="判断"/>
</form>
</html>The above is the detailed content of PHP determines whether a prime number is. For more information, please follow other related articles on the PHP Chinese website!
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