PROSAGA码农传奇-C/C++-找到一种方法将push_back匹配的地图中的键和值匹配到矢量中

您可以使用
std::copy_if
在

无需手动编写显式循环。也过去了
dictionary
通过（常量）引用来避免不必要的复制：


    
  #include <algorithm>
include 
include 
include 
// You’ll need C++14 to use auto const& kv in your lambda expression
std::vector>>
getIfPresentPartOfSpeech(
    const std::multimap>&
        dictionary,
    const std::string& name)
{
    std::vector<
        std::pair>>
        res;
    std::copy_if(begin(dictionary), end(dictionary), std::back_inserter(res),
                 & { return kv.second.first == name; });
    return res;
}
//test
int main()
{
    std::multimap> dictionary{
        {“first”, {“abc”, “def”}},
        {“second”, {“123”, “456”}},
        {“first”, {“asdf”, “fdas”}},
        {“thrid”, {“abc”, “123”}},
    };
    auto res = getIfPresentPartOfSpeech(dictionary, “abc”);
    for (auto& x : res)
        std::cout << x.first << “ “ << x.second.first << “ “ << x.second.second
                  << “\n”;
}
</code>


  
    使用像@aep这样的结构会更加清晰。你需要一个额外的转换构造函数才能使用它
     
      std::copy_if
    
    ：
  

   
    
      struct Response {
    std::string key;
    std::pair value;
    // Provide a conversion constructor that convert your dictionary multimap
    // key-value pair into a Response object
    Response(const std::pair>& kv)
    : key{kv.first}, value{kv.second}
    {}
};
std::vector getIfPresentPartOfSpeech(
    const std::multimap>&
        dictionary,
    const std::string& name)
{
    std::vector res;
    std::copy_if(begin(dictionary), end(dictionary), std::back_inserter(res),
                 & { return kv.second.first == name; });
    return res;
}
</code>