PHP中英混合字符串截取函数代码

function get_word($string, $length, $dot = '..',$charset='gbk') { 
if(strlen($string) <= $length) { 
return $string; 
} 
$string = str_replace(array('　',' ', '&', '"', '<', '>'), array('','','&', '"', '<', '>'), $string); 
$strcut = ''; 
if(strtolower($charset) == 'utf-8') { 
$n = $tn = $noc = 0; 
while($n < strlen($string)) { 
$t = ord($string[$n]); 
if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) { 
$tn = 1; $n++; $noc++; 
} elseif(194 <= $t && $t <= 223) { 
$tn = 2; $n += 2; $noc += 2; 
} elseif(224 <= $t && $t < 239) { 
$tn = 3; $n += 3; $noc += 2; 
} elseif(240 <= $t && $t <= 247) { 
$tn = 4; $n += 4; $noc += 2; 
} elseif(248 <= $t && $t <= 251) { 
$tn = 5; $n += 5; $noc += 2; 
} elseif($t == 252 || $t == 253) { 
$tn = 6; $n += 6; $noc += 2; 
} else { 
$n++; 
} 
if($noc >= $length) { 
break; 
} 
} 
if($noc > $length) { 
$n -= $tn; 
} 
$strcut = substr($string, 0, $n); 
} else { 
for($i = 0; $i < $length; $i++) { 
$strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i]; 
} 
} 
return $strcut.$dot; 
} 
$str = "欢迎 visit 简明 nowamagic"; 
$str_result = get_word($str, 12); 
echo $str_result;

测试运行结果：
欢迎 visit..