php判断字符串编码是否为utf8的函数举例

<?php
/**
* 判断字符串编码
* edit by www.jbxue.com
*/
function is_utf8($word)
{
 if(preg_match("/^([".chr(228)."-".chr(233)."]{1}[".chr(128)."-".chr(191)."]{1}[".chr(128)."-".chr(191)."]{1}){1}/",$word) == true || preg_match("/([".chr(228)."-".chr(233)."]{1}[".chr(128)."-".chr(191)."]{1}[".chr(128)."-".chr(191)."]{1}){1}$/",$word) == true || preg_match("/([".chr(228)."-".chr(233)."]{1}[".chr(128)."-".chr(191)."]{1}[".chr(128)."-".chr(191)."]{1}){2,}/",$word) == true) {
  return true;
 }else {
  return false;
 }
}
$t = 'wangbin';
//$t = iconv('GB2312','UTF-8',$t)
var_dump(is_utf8($t));
?>

<?php
/**
* 检测是否utf8编码
* edit by www.jbxue.com
*/
 function is_utf8($string) {
     return preg_match('%^(?:
             [\x09\x0A\x0D\x20-\x7E]                 # ASCII
         | [\xC2-\xDF][\x80-\xBF]                 # non-overlong 2-byte
         |     \xE0[\xA0-\xBF][\x80-\xBF]             # excluding overlongs
         | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}     # straight 3-byte
         |     \xED[\x80-\x9F][\x80-\xBF]             # excluding surrogates
         |     \xF0[\x90-\xBF][\x80-\xBF]{2}     # planes 1-3
         | [\xF1-\xF3][\x80-\xBF]{3}             # planes 4-15
         |     \xF4[\x80-\x8F][\x80-\xBF]{2}     # plane 16
     )*$%xs', $string);     
}
?>