php 如何检查字符串的字符集？
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How to check the charset of string?
提问by ZA.
How do I check if the charset of a string is UTF8?
如何检查字符串的字符集是否为 UTF8？
采纳答案by ZA.
function is_utf8($string) {
return preg_match('%^(?:
[\x09\x0A\x0D\x20-\x7E] # ASCII
| [\xC2-\xDF][\x80-\xBF] # non-overlong 2-byte
| \xE0[\xA0-\xBF][\x80-\xBF] # excluding overlongs
| [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte
| \xED[\x80-\x9F][\x80-\xBF] # excluding surrogates
| \xF0[\x90-\xBF][\x80-\xBF]{2} # planes 1-3
| [\xF1-\xF3][\x80-\xBF]{3} # planes 4-15
| \xF4[\x80-\x8F][\x80-\xBF]{2} # plane 16
)*$%xs', $string);
}
}
I have checked. This function is effective.
我检查过。此功能有效。
回答by soulmerge
Don't reinvent the wheel. There is a builtin function for that task: mb_check_encoding().
不要重新发明轮子。该任务有一个内置函数：mb_check_encoding().
mb_check_encoding($string, 'UTF-8');
回答by Stefan Gehrig
Just a side note:
只是一个旁注：
You cannot determine if a given string is encoded in UTF-8. You only can determine if a given string is definitively notencoded in UTF-8. Please see a related question here:
您无法确定给定的字符串是否以 UTF-8 编码。您只能确定给定的字符串是否明确未以 UTF-8 编码。请在此处查看相关问题：
You cannot detect if a given string (or byte sequence) is a UTF-8 encoded text as for example each and every series of UTF-8 octets is also a valid (if nonsensical) series of Latin-1 (or some other encoding) octets. However not every series of valid Latin-1 octets are valid UTF-8 series.
您无法检测给定的字符串（或字节序列）是否是 UTF-8 编码的文本，例如每个 UTF-8 八位字节系列也是一个有效的（如果是荒谬的）Latin-1（或其他一些编码）系列八位字节。然而，并非所有有效的 Latin-1 八位字节系列都是有效的 UTF-8 系列。
回答by nikc.org
Better yet, use both of the above solutions.
更好的是，使用上述两种解决方案。
function isUtf8($string) {
if (function_exists("mb_check_encoding") && is_callable("mb_check_encoding")) {
return mb_check_encoding($string, 'UTF8');
}
return preg_match('%^(?:
[\x09\x0A\x0D\x20-\x7E] # ASCII
| [\xC2-\xDF][\x80-\xBF] # non-overlong 2-byte
| \xE0[\xA0-\xBF][\x80-\xBF] # excluding overlongs
| [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte
| \xED[\x80-\x9F][\x80-\xBF] # excluding surrogates
| \xF0[\x90-\xBF][\x80-\xBF]{2} # planes 1-3
| [\xF1-\xF3][\x80-\xBF]{3} # planes 4-15
| \xF4[\x80-\x8F][\x80-\xBF]{2} # plane 16
)*$%xs', $string);
}
回答by Jyothish V
mb_detect_encoding($string);will return the actual character set of $string. mb_check_encoding($string, 'UTF-8');will return TRUEif character set of $stringis UTF-8 else FALSE
mb_detect_encoding($string);将返回 的实际字符集$string。如果字符集为 UTF-8mb_check_encoding($string, 'UTF-8');则返回TRUE，否则返回FALSE$string
回答by David Bélanger
None of the above answers are correct. Yes, they may be working. If you take the answer with the preg_replacefunction, are you trying to kill your server if you process a lot of stirng ? Use this pure PHP function with no regex, work 100% of the time and it's way faster.
以上答案都不对。是的，他们可能正在工作。如果你用preg_replace函数来回答，如果你处理了很多搅拌，你是否试图杀死你的服务器？使用这个没有正则表达式的纯 PHP 函数，可以 100% 地工作，而且速度更快。
if(function_exists('grk_Is_UTF8') === FALSE){
function grk_Is_UTF8($String=''){
# On va calculer la longeur de la cha?ne
$Len = strlen($String);
# On va boucler sur chaque caractère
for($i = 0; $i < $Len; $i++){
# On va aller chercher la valeur ASCII du caractère
$Ord = ord($String[$i]);
if($Ord > 128){
if($Ord > 247){
return FALSE;
} elseif($Ord > 239){
$Bytes = 4;
} elseif($Ord > 223){
$Bytes = 3;
} elseif($Ord > 191){
$Bytes = 2;
} else {
return FALSE;
}
#
if(($i + $Bytes) > $Len){
return FALSE;
}
# On va boucler sur chaque bytes / caractères
while($Bytes > 1){
# +1
$i++;
# On va aller chercher la valeur ASCII du caractère / byte
$Ord = ord($String[$i]);
if($Ord < 128 OR $Ord > 191){
return FALSE;
}
# Parfait
$Bytes--;
}
}
}
# Vrai
return TRUE;
}
}
回答by Haim Evgi
if its send to u from server
如果它从服务器发送给你
echo $_SERVER['HTTP_ACCEPT_CHARSET'];
