C++ 无法让 regex_match 工作

Question

在我的代码中，我想根据封闭的 <> 括号处理 stirngs。为此，我想遍历字符串并一个一个地替换括号并根据括号内的内容做一些事情。

string msg = "This is an <red>Example<> message. For <blue>exampleness' sake<>.";
std::regex rexpr("<[a-zA-Z]*>");

// replace the first set of <> with %c, return the non-replaced version, and process it.
while(true){
    std::smatch smatch;
    // cant find any matches...
    std::regex_match(msg, smatch, rexpr);
    string key = smatch[0]; // this is empty from the start.

    if(key.empty()) break; // no more keys, break.

    // replace <...>
    std::regex_replace(msg, rexpr, "%c", std::regex_constants::format_first_only);

    if(key.size() == 2) continue; // closing brackets, nothing to process

    // cut the brackets
    key = key.substr(1, key.size() - 1);

    // process the key.
    // ... 
}

Answer 1

你需要在你想要捕获的东西两边加上括号():

string msg = "This is an <red>Example<> message. For <blue>exampleness' sake<>.";
std::regex rexpr("(<[a-zA-Z]*>)");

smatch match;
if( regex_search(msg, match, rexpr) ) {
        cout << match[0] << endl;
}

输出:

<red>