参考：
https://www.cnblogs.com/xsphehe/p/5682004.html
示例：
/** * ?参数说明 * ?$string ?欲截取的字符串 * ?$sublen ?截取的长度 * ?$start ??从第几个字节截取，默认为0 * ?$code ???字符编码，默认UTF-8 */// $str="哈哈，帅哥在此！"; // echo cut_str($str, 30, 0, ‘gb2312‘); ?// gb2312字符编码// echo cut_str($str,30,0) ?//utf-8字符编码// 参考：https://www.cnblogs.com/xsphehe/p/5682004.htmlfunction cut_str($string, $sublen=30, $start = 0, $code = ‘UTF-8‘) { ???if ($code == ‘UTF-8‘) { ???????$pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/"; ???????preg_match_all($pa, $string, $t_string); ???????if (count($t_string[0]) - $start > $sublen) return join(‘‘, array_slice($t_string[0], $start, $sublen)) . "....."; ???????return join(‘‘, array_slice($t_string[0], $start, $sublen)); ???} else { ???????$start = $start * 2; ???????$sublen = $sublen * 2; ???????$strlen = strlen($string); ???????$tmpstr = ‘‘; ???????for ($i = 0; $i < $strlen; $i++) { ???????????if ($i >= $start && $i < ($start + $sublen)) { ???????????????if (ord(substr($string, $i, 1)) > 129) { ???????????????????$tmpstr.= substr($string, $i, 2); ???????????????} else { ???????????????????$tmpstr.= substr($string, $i, 1); ???????????????} ???????????} ???????????if (ord(substr($string, $i, 1)) > 129) $i++; ???????} ???????if (strlen($tmpstr) < $strlen) $tmpstr.= ""; ???????return $tmpstr; ???}}php---截取描述方法
原文地址：https://www.cnblogs.com/e0yu/p/9840429.html