PHP自定义函数round_pad_zero 小数位四舍五入并补零

<?php
/**
* 小数位四舍五入并补零
* by www.jb200.com
*/
function round_pad_zero($num, $precision) 
{ 
    if ($precision < 1) { 
        return round($num, 0); 
    } 
    $r_num = round($num, $precision); 
    $num_arr = explode('.', "$r_num"); 
    if (count($num_arr) == 1) { 
        return "$r_num" . '.' . str_repeat('0', $precision); 
    } 
    $point_str = "$num_arr[1]"; 
    if (strlen($point_str) < $precision) { 
        $point_str = str_pad($point_str, $precision, '0'); 
    } 
    return $num_arr[0] . '.' . $point_str; 
} 
//调用示例 
echo round_pad_zero(3223342.506, 4);