如果有约200个字(连符号、中、英文)
请问如何截取指定UTF-8中文的字符串?

如要头100个
<?php
$len=100;
$newStr=mb_substr($str,0,$len);
?>

方法1:

 

$newStr=mb_substr($str,0,$len, 'utf-8 ');

 

方法2:

 

如果服务器不支持mbstring扩展，就用下面这个函数

function   subString_UTF8($str,   $start,   $lenth)
        {
                $len   =   strlen($str);
                $r   =   array();
                $n   =   0;
                $m   =   0;
                for($i   =   0;   $i   <   $len;   $i++)   {
                        $x   =   substr($str,   $i,   1);
                        $a     =   base_convert(ord($x),   10,   2);
                        $a   =   substr( '00000000 '.$a,   -8);
                        if   ($n   <   $start){
                                if   (substr($a,   0,   1)   ==   0)   {
                                }elseif   (substr($a,   0,   3)   ==   110)   {
                                        $i   +=   1;
                                }elseif   (substr($a,   0,   4)   ==   1110)   {
                                        $i   +=   2;
                                }
                                $n++;
                        }else{
                                if   (substr($a,   0,   1)   ==   0)   {
                                        $r[   ]   =   substr($str,   $i,   1);
                                }elseif   (substr($a,   0,   3)   ==   110)   {
                                        $r[   ]   =   substr($str,   $i,   2);
                                        $i   +=   1;
                                }elseif   (substr($a,   0,   4)   ==   1110)   {
                                        $r[   ]   =   substr($str,   $i,   3);
                                        $i   +=   2;
                                }else{
                                        $r[   ]   =   ' ';
                                }
                                if   (++$m   > =   $lenth){
                                        break;
                                }
                        }
                }
                return   $r;
        }   //   End   subString_UTF8;
}//   End   String

返回的是个数组，显示的join一下:
echo   join( ' ',subString_UTF8($str,   $start,   $lenth));