给定一个数字，我们必须找到它的阶乘。
查找阶乘的公式： 5！（5的方格）= 5x4x3x2x1 = 120
示例
Input: 5 Output: 120
<?php
//查找数字阶乘的程序
//在这里，我们正在设计一个功能
//将数字作为参数并返回
//该数字的阶乘
//功能：getFactorial-
function getFactorial($num){
//声明一个变量并赋值为1-
$factorial = 1;
for($loop = 1; $loop <= $num; $loop++)
$factorial = $factorial * $loop;
return $factorial;
}
//测试上述功能的主代码
$number = 1;
print_r("Factorial of ".$number. " is = ".getFactorial($number). "\n");
$number = 2;
print_r("Factorial of ".$number. " is = ".getFactorial($number). "\n");
$number = 3;
print_r("Factorial of ".$number. " is = ".getFactorial($number). "\n");
$number = 4;
print_r("Factorial of ".$number. " is = ".getFactorial($number). "\n");
$number = 5;
print_r("Factorial of ".$number. " is = ".getFactorial($number). "\n");
?>输出结果
Factorial of 1 is = 1 Factorial of 2 is = 2 Factorial of 3 is = 6 Factorial of 4 is = 24 Factorial of 5 is = 120