[英]How to check if a string can safely be converted in another character set without loss?
Is it possible, prior to converting a string from a charset to another, to know whether this conversion will be lossless? 在将字符串从字符集转换为另一个字符串之前,是否有可能知道此转换是否无损?
If I try to convert an UTF-8 string to latin1, for example, the chars that can't be converted are replaced by ?
例如,如果我尝试将UTF-8字符串转换为latin1,则无法转换的字符将替换为
?
. 。 Checking for
?
检查
?
in the result string to find out if the conversion was lossless is obviously not a choice. 在结果字符串中找出转换是否无损是显然不是一个选择。
The only solution I can see right now is to convert back to the original charset, and compare to the original string: 我现在能看到的唯一解决方案是转换回原始字符集,并与原始字符串进行比较:
function canBeSafelyConverted($string, $fromEncoding, $toEncoding)
{
$encoded = mb_convert_encoding($string, $toEncoding, $fromEncoding);
$decoded = mb_convert_encoding($encoded, $fromEncoding, $toEncoding);
return $decoded == $string;
}
This is just a quick&dirty one though, that may come with unexpected behaviours at times, and I guess there might be a cleaner way to do this with mbstring , iconv , or any other library. 这只是一个快速而肮脏的问题,有时可能会出现意外行为,我想可能有更简洁的方法可以使用mbstring , iconv或任何其他库。
An alternative way is to set up your own error handler with set_error_handler(). 另一种方法是使用set_error_handler()设置自己的错误处理程序。 If you use iconv() on the string it will throw a notice if it can not be fully converted that you can catch there and react to in your code.
如果你在字符串上使用iconv(),它会抛出一个通知,如果它无法完全转换,你可以捕到它并在你的代码中做出反应。
Or you could just count the number of question marks before and after encoding. 或者您可以只计算编码前后的问号数量。 Or call iconv() with //IGNORE and count the number of characters.
或者使用// IGNORE调用iconv()并计算字符数。
None of the suggestions much more elegant than yours, but gets rid of the double processing. 没有比你更优雅的建议,但摆脱了双重处理。
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