php截取字符串方法, 让英文,中文,中英文混合差不多长

 1 /*
 2  * functions for limiting maximal text length
 3 */
 4 function strmaxtextlen($input, $len = 60) {
 5    $bytelen = mb_strlen($input, ‘ASCII‘);
 6    $strlen = JString::strlen($input);  
 7            
 8    if($bytelen == $strlen) {
 9       /* only ascii. Most utf-8 chars are 3 bytes long, so we can cut at least 2 times of $len */
10       if($bytelen > 2* $len)
11          return mb_strcut($input, 0, 2 * $len)."...";
12    }
13    else {
14       /* either mixed or only multiple-byte chars, we cut x times of $len */
15       $rlen = $bytelen/$strlen;       
16       if($bytelen > $rlen * $len)
17          return mb_strcut($input, 0, $rlen * $len)."...";
18    }
19               
20    return $input;
21 }