PHP uses function to determine whether a number is prime

Prime numbers are also called prime numbers. A natural number greater than 1 that is not divisible by other natural numbers except 1 and itself is called a prime number.

First of all, know what a prime number is, a natural number greater than 1, the conditions for a number that cannot be divisible by other natural numbers except 1 and itself, To determine whether the number is prime. (Recommended learning: PHP programming from entry to proficiency)

<?php
// 判断一个数是否是素数,利用该函数的功能,求出1-200之间的所有素数
function suShu($x)
{
    $count = 0;
    for ($i = 1; $i <= $x; $i++) //循环
    {
        if ($x % $i == 0) { //取余
            $count++;
        }
    }
    if ($count == 2) { //取余等于2为true,否则为false
        return true;
    }
    return false;
}

$count = 0;
for ($i = 1; $i <= 200; $i++) //输出1-200之间的素数
{
    if (suShu($i)) {
        echo $i . &#39;1&#39;;
        $count++;
    }
}
echo &#39;<br>&#39;;
echo &#39;一共有&#39; . $i . &#39;个素数&#39;;

?>

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