PHP 添加前导0，去掉前导0
当然不只是可以加0，去0，可以添加任何前导
添加前导：
使用PHP自己提供的函数：
str_pad
(PHP 4 >= 4.0.1, PHP 5)
str_pad -- Pad a string to a certain length with another string
Description
string str_pad ( string input, int pad_length [, string pad_string [, int pad_type]] )
This functions returns the input string padded on the left, the right, or both sides to the specified padding length. If the optional argument pad_string is not supplied, the input is padded with spaces, otherwise it is padded with characters from pad_string up to the limit.
Optional argument pad_type can be STR_PAD_RIGHT, STR_PAD_LEFT, or STR_PAD_BOTH. If pad_type is not specified it is assumed to be STR_PAD_RIGHT.
If the value of pad_length is negative or less than the length of the input string, no padding takes place.
例：
<?php
$input = "Alien";
echo str_pad($input, 10); // produces "Alien "
echo str_pad($input, 10, "-=", STR_PAD_LEFT); // produces "-=-=-Alien"
echo str_pad($input, 10, "_", STR_PAD_BOTH); // produces "__Alien___"
echo str_pad($input, 6 , "___"); // produces "Alien_"
?>
去掉前导
使用正则
参考：
$pattern = “/(0+)(\d+)/i”;
$replacement = “\$2″;
$qid = preg_replace($pattern,$replacement,$qid);
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Tags: 前导