PHP中GBK和UTF8编码处理

以下为引用的内容：

 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:

PLAIN TEXT
PHP:
preg_replace("/([x80-xff])/","",$str);
preg_replace("/([u4e00-u9fa5])/","",$str);

二、代码例子

PLAIN TEXT
PHP:
//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++){