一个关于 PHP trim 函数的问题

This topic created in 2151 days ago, the information mentioned may be changed or developed.

代码非常简单：
<?php
$url='http://10.100.11.5/xapi.git';
$tmp=trim($url,'.git');
var_dump($tmp);
$url='http://10.100.11.5/xapi';
$tmp=trim($url,'git');
var_dump($tmp);

执行后的结果：
root@debian10:/var/www/html# php 7.php
string(22) "http://10.100.11.5/xap"
string(22) "http://10.100.11.5/xap"
问题：为什么会把字符串结尾的 i 字符给吞了，

环境 php 7.3 php5.6 均测试如此

PHP

tmp

URL

trim

19 replies • 2020-07-20 09:38:09 +08:00

geeglo

Jul 17, 2020

trim 的常见误区，的第二参数不会作为整体去移除。而是每个字符单独左右移除

nilai

Jul 17, 2020

@geeglo 若要整体移除呢？用什么函数代替？

zachlhb

Jul 17, 2020 via Android

@nilai rtrim

geeglo

Jul 17, 2020

没有，自己写。

weirdo

Jul 17, 2020

@nilai str_replace preg_replace
$url = str_replace('.git', '', $url)

U7Q5tLAex2FI0o0g

Jul 17, 2020

手册有说明：
https://www.php.net/manual/en/function.trim.php#refsect1-function.trim-notes

Note: Possible gotcha: removing middle characters
Because trim() trims characters from the beginning and end of a string, it may be confusing when characters are (or are not) removed from the middle. trim('abc', 'bad') removes both 'a' and 'b' because it trims 'a' thus moving 'b' to the beginning to also be trimmed. So, this is why it "works" whereas trim('abc', 'b') seemingly does not.

rming

Jul 17, 2020

$url = 'http://10.100.11.5/xapi.git';
$tmp = preg_replace("/\.git$/", "", $url);

rming

Jul 17, 2020

preg_replace("/^start|end$/", "", "start content end")

nilai

Jul 17, 2020

@weirdo str_replace 不适合， str_replace 会替换字符串中的所有， trim 功能中只去头尾

nilai

Jul 17, 2020

@rming preg_replace 能实现。

nilai

Jul 17, 2020

@rming 简单写了个函数这样可好？
function strim($string,$removestring){
if (!is_string($string) || !is_string($removestring)){
return $string;
}
$result = preg_replace("/^{$removestring}|{$removestring}$/", "", $string);
return $result;
}

nilai

Jul 17, 2020

改成这样可能会更好点。
function strim($string,$removestring=''){
if (!is_string($string)){
return $string;
}
if (!$removestring){
return trim($string);
}
$result = preg_replace("/^{$removestring}|{$removestring}$/", "", $string);
return $result;
}

KasuganoSoras

Jul 17, 2020

@nilai #9 不要忘了 str_replace 有 count 参数
$url = str_replace(".git", "", $url, 1);
这样就只会替换一次了，另外如果你只是想单纯去掉结尾 .git 的话
$url = substr($url, -4, 4) == ".git" ? substr($url, 0, strlen($url) - 4) : $url;
完事了