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我正在使用 boost::regex_match 并且试图找到一个函数来获取正则表达式停止匹配的位置。我在 boost::match_results 对象中找不到任何属性，但有几个代码片段使用 boost::regex_search 来显示子匹配项。我的实施是否走在正确的道路上，还是我必须做一些不同的事情才能实现这一目标？我的代码如下所示：

int main(int args, char** argv)
{
    boost::match_results<std::string::const_iterator> what;

    if(args == 3) 
    {
        std::string text(argv[1]);
        boost::regex expression(argv[2]);

        std::cout << "Text : " << text << std::endl;
        std::cout << "Regex: " << expression << std::endl;

        if(boost::regex_match(text, what, expression, boost::match_default) != 0) 
        {
            int i = 0;

            for(boost::match_results<std::string::const_iterator>::const_iterator it=what.begin(); it!=what.end(); ++it) 
            {
                std::cout << "[" << (i++) << "] " << it->str() << std::endl;
            }
            std::cout << "Matched!" << std::endl;
        } 
        else 
        {
            std::string::const_iterator start = text.begin();
            std::string::const_iterator end   = text.end();

            while(boost::regex_search(start, end, what, expression)) 
            {
                std::string submatch(what[1].first, what[1].second);
                std::cout << submatch << std::endl;
                start = what[0].second;
            }
            std::cout << "Didn't match!" << std::endl;
        }
    } //if(args == 3)
    else 
    {
        std::cout << "Invalid usage! $> ./boost-regex <text> <regex>" << std::endl;
    }
    return 0;
}

输出：

$> ./boost_regex "We're building it up to burn it down" ".*(build.*)(to.*)(burn.*)"
Text : We're building it up to burn it down
Regex: .*(build.*)(to.*)(burn.*)
[0] We're building it up to burn it down
[1] building it up
[2] to
[3] burn it down
Matched!

$> ./boost_regex "We're building it up to burm it down" ".*(build.*)(to.*)(burn.*)"
Text : We're building it up to burm it down
Regex: .*(build.*)(to.*)(burn.*)
Didn't match!

对于最后一个输入，我想要类似于：

Text : We're building it up to burm it down
Regex: .*(build.*)(to.*)(burn.*)
[0] We're building it up to
[1] building it up
[2] to
Didn't match!

提前致谢 ...

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1 回答 1

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首先，您的示例中的正则表达式有问题。因为它无法匹配(burn.*)子组，所以整个正则表达式无法匹配任何内容，并且不返回任何结果。添加一个“？” after(burn.*)将使前两个子组匹配，而第三个子组不匹配。

我会查看 rubular.com，它是调整正则表达式并实时观察它们工作的好工具。

要测试子组是否参与匹配，您需要检查sub_match::matchedfor 循环中的布尔变量，如果子组匹配，则为真。在此处查看 boost::submatch 的文档

希望这会有所帮助，这实际上是我的第一篇 Stackoverflow 帖子、答案或评论。:)

于 2012-07-18T02:28:29.910 回答