PHP utf-8中文截取无乱码(字符串判断版本）

/*E4 B8 AD E5 9B BD   中国1110 0100    10111000   101011011110 0101    100110111011110161  a0011 11010xxx xxxx ,1个字节110xx xxxx , 2个字节1110 xxxx, 31111 0xxxx 4...*/<pre name="code" class="php">$str = '中华人aaa民共b和国,c万岁';function utf8sub($str,$len){if($len <=0) return '';$length = strlen($str);$offset=0;$chars=0;$res='';while($chars<$len && $offset<$length){$heigh = decbin(ord(substr($str, $offset,1)));echo $heigh ,'</br>';if(strlen($heigh)<8){$count=1;}else if(substr($heigh,0,3) == '110'){$count=2;}else if(substr($heigh,0,4) == '1110'){$count=3;}else if(substr($heigh,0,5) == '11110'){$count=4;}else if(substr($heigh,0,6) == '111110'){$count=5;}else if(substr($heigh,0,7) == '1111110'){$count=6;}$res .= substr($str, $offset,$count);$chars += 1;$offset += $count;}return $res;}echo utf8sub($str,10);