使用正则表达式的一大优点是处理棘手的情况下，像＆放大器;＃38;＃38; 实体更换不重复，这是一个单一的步骤。正则表达式也将是相当有效：两个主角是固定的，所以它会快速跳过任何无法与＆放大器开始;＃。最后，正则表达式的解决方案是一个没有很多的惊喜为将来的维护者。

The big advantage of using a regex is to deal with the tricky cases like & Entity replacement isn't iterative, it's a single step. The regex is also going to be fairly efficient: the two lead characters are fixed, so it will quickly skip anything not starting with &#. Finally, the regex solution is one without a lot of surprises for future maintainers.

我会说一个正则表达式是正确的选择。

I'd say a regex was the right choice.

这是***的正则表达式，关​​系吗？你知道你需要两位数字，如果你有3个数字，第一个将是1.可打印的ASCII毕竟是＆放大器;＃32; - ＆安培;＃126; 。出于这个原因，你可以考虑＆放大器;＃1 \\ D \\ D;

Is it the best regex, though? You know you need two digits and if you have 3 digits, the first one will be a 1. Printable ASCII is after all  -~. For that reason, you could consider &#1?\d\d;.

至于更换的内容，我会使用basic算法描述的boost ::正则表达式替换:: ：

As for replacing the content, I'd use the basic algorithm described for boost::regex::replace :

For each match // Using regex_iterator<>
    Print the prefix of the match
    Remove the first 2 and last character of the match (&#;)
    lexical_cast the result to int, then truncate to char and append.

Print the suffix of the last match.