首先分别解释下,

trim过滤字符串两端,
rtrim过滤字符串尾部,=chop()
ltrim过滤字符串首部.

过滤字符串中键的咚咚就只能用str_replace咯.
举个例子说明下,

PHP代码
复制代码 代码如下:
$str = '123,333,234,';
echo rtrim($str, ',');

rtrim实例代码2
复制代码 代码如下:
<?php
$text = "\t\tThese are a few words :) ...  ";
$trimmed = rtrim($text);
// $trimmed = "\t\tThese are a few words :) ..."
$trimmed = rtrim($text, " \t.");
// $trimmed = "\t\tThese are a few words :)"
$clean = rtrim($binary, "\x00..\x1F");
// trim the ASCII control characters at the end of $binary
// (from 0 to 31 inclusive)
?>