C++11 emplace_back on vector?

Question

Consider the following program:

#include 
#include 

using namespace std;

struct T
{
    int a;
    double b;
    string c;
};

         


        

Answer 1

You can use the {} syntax to initialize the new element:

V.emplace_back(T{42, 3.14, "foo"});

This may or may not be optimized, but it should be.

You have to define a constructor for this to work, note that with your code you can't even do:

T a(42, 3.14, "foo");

But this is what you need to have emplace work.

so just:

struct T { 
  ...
  T(int a_, double b_, string c_) a(a_), b(b_), c(c_) {}
}

will make it work the desired way.