c++ - emplace_back not working with std::vector

I am trying to do emplace_back into a std::vector>, but could not find the right syntax to do it.

#include

push_back works here, but not emplace_back. How can I get emplace_back working?

Answer

One can achieve that using a helper function as follows:

 #include 

The problem was when we write:

v.emplace_back({{1,2}});  // here {{1,2}} does not have a type.

the compiler is not able to deduce the type of the argument, and it can't decide which constructor to call.

The underlying idea is that when you write a function like

template
void f(T) {}

and use it like

f( {1,2,3,4} ); //error

you will get compiler error, as {1,2,3,4} does have a type.

But if you define your function as

template
void f(std::initializer_list) {}

 f( {1,2,3,4} );

then it compiles perfectly.