gbk与utf-8的转换

GBK 的编码范围(GB2312/GB18030)
\x00-\xff GBK双字节编码范围
\x20-\x7f ASCII
\xa1-\xff 中文
\x80-\xff 中文

UTF-8 的编码范围(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



现在我们来看一些PHP处理gbk和utf-8的代码例子



正则例子:
preg_replace("/([\x80-\xff])/","",$str);
preg_replace("/([u4e00-u9fa5])/","",$str);

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 $s = substr($str, $i, 1);
if (preg_match("/[\x80-\xff]/", $s)) ++$i;
++$count;
}
return $count;
}



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;
}

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

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));
}