Question

I have a very basic question.

Lets take the following code snippet:

#include<iostream>
int main()
{
   std::cout<<"Hello world \n";
}

In the above program, does ‘iostream’ gets compiled?

If it compiles, isn’t it a overhead?

Because anyways we are not going to change anything in iostream, but it gets compiled everytime :-/

Please help me understand this.

Answer 1

The include basically pastes the content of <iostream> in your source file, so you could say it gets compiled.

If it compiles, isn’t it a overhead?

It takes longer, but you need the include because you use std::cout. This is one of the reasons why you should only include what you need and use declarations instead wherever possible.

What you can do is look into precompiled headers.