如何循环通过std :: regex_search的结果？ [英] How do I loop through results from std::regex_search?

问题描述

调用 std :: regex_search 后，我只能从 std :: smatch 由于某种原因：

After calling std::regex_search, I'm only able to get the first string result from the std::smatch for some reason:

Expression.assign("rel=\"nofollow\">(.*?)</a>");
if (std::regex_search(Tables, Match, Expression))
{
    for (std::size_t i = 1; i < Match.size(); ++i)
        std::cout << Match[i].str() << std::endl;
}

所以我试着用另一种方法 - 使用迭代器：

So I tried to do it another way - with an iterator:

const std::sregex_token_iterator End;
Expression.assign("rel=\"nofollow\">(.*?)</a>");
for (std::sregex_token_iterator i(Tables.begin(), Tables.end(), Expression); i != End; ++i)
{
    std::cout << *i << std::endl;
}

这样做通过每个匹配，而不仅仅是我以后的捕获。肯定是另一种方式，而不是在循环中迭代器元素上做另一个 std :: regex_search ？

This does go through every match, but it also gives me the whole matching string instead of just the capture that I was after. Surely must be another way than having to do another std::regex_search on the iterator element in the loop?

提前感谢。

推荐答案

regex_token_iterator 每次迭代都返回子匹配。此参数的默认值为0，在C ++（和许多其他）正则表达式的情况下意味着整个匹配。如果你想得到第一个捕获的submatch，只需传递1到构造函数：

regex_token_iterator takes an optional fourth argument specifying which submatch is returned for each iteration. The default value of this argument is 0, which in case of the C++ (and many other) regexes means "the whole match". If you want to get the first captured submatch, simply pass 1 to the constructor:

for (std::sregex_token_iterator i(Tables.begin(), Tables.end(), Expression, 1); i != End; ++i)
{
    std::cout << *i << std::endl; // *i only yields the captured part
}

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