PHP获取字符串中英文混合长度

/**

* @param $str string 字符串

* @param $$charset string 编码

* @return 返回长度，1中文=1位，2英文=1位

*/

function strLength($str,$charset='utf-8'){

if($charset=='utf-8') $str = iconv('utf-8','gb2312',$str);

$num = strlen($str);

$cnNum = 0;

for($i=0;$i<$num;$i++){

if(ord(substr($str,$i+1,1))>127){

$cnNum++;

$i++;

}

}

$enNum = $num-($cnNum*2);

$number = ($enNum/2)+$cnNum;

return ceil($number);

}