How do I write a map literal in C++11? [duplicate]

Question

In Python, I can write a map literal like this:

mymap = {"one" : 1, "two" : 2, "three" : 3} 

How can I do the equivalent in C++11?

Answer 1

You can actually do this:

std::map<std::string, int> mymap = {{"one", 1}, {"two", 2}, {"three", 3}}; 

What is actually happening here is that std::map stores an std::pair of the key value types, in this case std::pair<const std::string,int>. This is only possible because of c++11's new uniform initialization syntax which in this case calls a constructor overload of std::pair<const std::string,int>. In this case std::map has a constructor with an std::intializer_list which is responsible for the outside braces.

So unlike python's any class you create can use this syntax to initialize itself as long as you create a constructor that takes an initializer list (or uniform initialization syntax is applicable)