php 字符串截取

 

function mySubStr($str, $maxWidth, $encoding='utf-8'){
   $strlen = mb_strlen($str);

   $newStr = '';
   for($pos = 0, $currwidth = 0; $pos < $strlen; ++$pos ){
    $ch = mb_substr($str, $pos, 1, $encoding);
    if ($currwidth + mb_strwidth($ch, $encoding) > $maxWidth) break;

    $newStr .= $ch;
    $currwidth += mb_strwidth($ch, $encoding) > 1 ? 2 : 1;
    }
    return $newStr;

   }