function substr_text($str, $start=0, $length, $charset="utf-8", $suffix=""){
if(function_exists("mb_substr")){//mb_substr函数不是php内置函数，需要加载php.mbstring.dll才能使用，否则报错
return mb_substr($str, $start, $length, $charset).$suffix;
}elseif(function_exists('iconv_substr')){
return iconv_substr($str,$start,$length,$charset).$suffix;
}else{
$re['utf-8'] = "/[x01-x7f]|[xc2-xdf][x80-xbf]|[xe0-xef][x80-xbf]{2}|[xf0-xff][x80-xbf]{3}/";
$re['gb2312'] = "/[x01-x7f]|[xb0-xf7][xa0-xfe]/";
$re['gbk'] = "/[x01-x7f]|[x81-xfe][x40-xfe]/";
$re['big5'] = "/[x01-x7f]|[x81-xfe]([x40-x7e]|xa1-xfe])/";
preg_match_all($re[$charset], $str, $match);
$slice = join("",array_slice($match[0], $start, $length));
return $slice.$suffix;
}
}
print_r(substr_text('字符串截取', 1, 3))