php怎么实现阶乘

1、php怎么实现阶乘，php计算1到8的阶乘1？

php计算1到8的阶乘1！+2！+3！+·····+8

每个语言必备阶乘，代码如下

$sum = 0;

for ($i = 1; $i < 9; $i++) {

$sum += jc($i);

}

echo $sum

function jc($num){

$tmp = 1;

$tmp2 = $tmp;

for ($i=1; $i < $num; $i++) {

if( $tmp < $num){

$tmp2 *= ($tmp+1);

++$tmp;

}

}

return $tmp2;

}