利用PHP函数计算中英文字符串长度

echo $str = 'PHP点点通';

echo strlen($str); //3*1+3*3=12
echo mb_strlen($str, 'gb2312'); //3*1+3*2=9
echo mb_strlen($str, 'utf-8'); //6

<?php
function _strlen($str)
{
preg_match_all("/./us", $str, $matches);
return count(current($matches));
}

echo _strlen("PHP点点通"); //6