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PHP中GBK和UTF8编码处理以及字符串截取

PHP编程中经常会遇到GBK和utf8编码的问题,而且在输出中也会涉及到中文字符串的截取。本文整理了一些PHP中判断GBK和UTF8编码以及截取字符串的程序。

一、编码范围

1. GBK (GB2312/GB18030)

\x00-\xff  GBK双字节编码范围
\x20-\x7f  ASCII
\xa1-\xff  中文
\x80-\xff  中文

2. UTF-8 (Unicode)

\u4e00-\u9fa5 (中文)
\x3130-\x318F (韩文
\xAC00-\xD7A3 (韩文)
\u0800-\u4e00 (日文)
ps: 韩文是大于[\u9fa5]的字符

正则例子:

preg_replace(“/([\x80-\xff])/”,””,$str);
preg_replace(“/([u4e00-u9fa5])/”,””,$str);

二、代码例子,提供一个截取字符串的PHP函数

//判断内容里有没有中文-GBK (PHP)

function check_is_chinese($s)
{
return preg_match('/[\x80-\xff]./', $s);
}

//获取字符串长度-GBK (PHP)

function gb_strlen($str)
{
$count = 0;
for($i=0; $i<strlen($str); $i++){
$s = substr($str, $i, 1);
if (preg_match("/[\x80-\xff]/", $s)) ++$i;
++$count;
}
return $count;
}

//截取字符串字串-GBK (PHP)
function gb_substr($str, $len){
$count = 0;
for($i=0; $i<strlen($str); $i++){
if($count == $len) break;
if(preg_match("/[\x80-\xff]/", substr($str, $i, 1))) ++$i;
++$count;
}
return substr($str, 0, $i);
}

//统计字符串长度-UTF8 (PHP)
function utf8_strlen($str) {
$count = 0;
for($i = 0; $i < strlen($str); $i++){
$value = ord($str[$i]);
if($value > 127) {
$count++;
if($value >= 192 && $value <= 223) $i++;
elseif($value >= 224 && $value <= 239) $i = $i + 2;
elseif($value >= 240 && $value <= 247) $i = $i + 3;
else die('Not a UTF-8 compatible string');
}
$count++;
}
return $count;
}

//截取字符串-UTF8(PHP)
function utf8_substr($str,$position,$length){
$start_position = strlen($str);
$start_byte = 0;
$end_position = strlen($str);
$count = 0;
for($i = 0; $i < strlen($str); $i++){
if($count >= $position && $start_position > $i){
$start_position = $i;
$start_byte = $count;
}
if(($count-$start_byte)>=$length) {
$end_position = $i;
break;
}
$value = ord($str[$i]);
if($value > 127){
$count++;
if($value >= 192 && $value <= 223) $i++;
elseif($value >= 224 && $value <= 239) $i = $i + 2;
elseif($value >= 240 && $value <= 247) $i = $i + 3;
else die('Not a UTF-8 compatible string');
}
$count++;
}
return(substr($str,$start_position,$end_position-$start_position));
}
//判断是否是有韩文-UTF-8 (JavaScript)
function checkKoreaChar(str) {
for(i=0; i<str.length; i++) {
if(((str.charCodeAt(i) > 0x3130 && str.charCodeAt(i) < 0x318F) || (str.charCodeAt(i) >= 0xAC00 && str.charCodeAt(i) <= 0xD7A3))) {
return true;
}
}
return false;
}

//判断是否有中文字符-GBK (JavaScript)
function check_chinese_char(s){
return (s.length != s.replace(/[^\x00-\xff]/g,"**").length);
}
/**
* 中文截取,支持gb2312,gbk,utf-8,big5
*
* @param string $str 要截取的字串
* @param int $start 截取起始位置
* @param int $length 截取长度
* @param string $charset utf-8|gb2312|gbk|big5 编码
* @param $suffix 是否加尾缀
**/
function csubstr($str, $start=0, $length, $charset="utf-8", $suffix=true)
{
if(function_exists("mb_substr"))
return mb_substr($str, $start, $length, $charset);
$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, $length));
if($suffix)
return $slice."&hellip;";
return $slice;
}

 



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