<?php
header('Content-Type:text/html;charset=utf-8');
function cutstr($str,$len){
if($len<0){return null;}
$chars = 0; //字符数量
$offset = 0;
$res = '';
while($chars < $len){
$high = decbin(ord(substr($str,$offset,1)));
if(strlen($high) < 8){
$count = 1;
}else if(substr($high,0,3) == '110'){
$count = 2;
}else if(substr($high,0,4)== '1110'){
$count = 3;
}
echo $count.'<br/>';
$res .= substr($str,$offset,$count);
$chars += 1;
$offset += $count;
}
return $res;
}
$str = '你好aaaaa';
echo cutstr($str,2);
?>
