std :: pair中有超过2个变量

Question

pair looks like this

std::vector<std::pair<uint64 /*id*/, std::string /*message*/>

and if i want 3 variables in vector ? Can i use pair or what ?

Thanks

Answer 1

If I have understood correctly you could use std::tuple declared in header <tuple> . For example

std::vector<std::tuple<uint64, std::string, SomeOtherType>> v;

Answer 2

In C++ sometimes I find quite useful to define trivial all-public data-only classes like

struct Event {
    unit32 id;
    std::string msg;
    uint32 time;
    Event() : id(0), msg(""), time(0) {} // If needed
    Event(uint32 id, const std::string& msg, uint32 time)
      : id(id), msg(msg), time(time) {}
};

Surely a bit of typing, but IMO way better than having to use e.second or std::get<1>(e) instead of e.msg everywhere in the code.

Writing is done once, reading many times. Saving writing time at the expense of increasing reading/understanding time is a Very Bad Idea.

Answer 3

If you don't want C++11, you can use

std::pair<uint64, std::pair<std::string, SomeOtherType> >

But this is as wrong as trying to put three values to a pair . Why I consider it wrong? A pair means two values. If you put three or any other number of values in a pair , you are doing something like this .