如果是只想输入中文的话，就这么写，要注意是分gb2312和utf-8的哦：
gb2312：if(!preg_match("/^[".chr(0xa1)."-".chr(0xff)."]+$/",$str))
utf-8 ：if(!preg_match("/^[\x{4e00}-\x{9fa5}]+$/u",$str))
去除特殊字符
$regex = "/(\/|\~|\!|\@|\#|\\$|\%|\^|\&|\*|\(|\)|\_|\+|\{|\}|\:|\<|\>|\?|\[|\]|\,|\.|\/|\;|\'|\`|\-|\=|\\|\||\"){2,}/";
$other = preg_replace($regex,"",$other);
$regex = "/(，|。|！|；|：|、|’|‘|【|】|《|》|？|@|#|￥|%|&|\*|（|）|\-|\+|\=|@|…){2,}/";
$other = preg_replace($regex,"",$other);