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 = " These are a few words :) ...  ";
$trimmed = rtrim($text);
// $trimmed = " These are a few words :) ..."
$trimmed = rtrim($text, " .");
// $trimmed = " These are a few words :)"
$clean = rtrim($binary, "x00..x1F");
// trim the ASCII control characters at the end of $binary
// (from 0 to 31 inclusive)
?>