My code works without #include <string>

[mortalwombat]

I am using Visual Studio 19. The code compiles and runs fine.

[Corendiel]

From https://stackoverflow.com/questions/16506095/do-i-have-to-use-include-string-beside-iostream

Yes, you have to include what you use. It’s not mandated that standard headers include one another (with a few exceptions IIRC). It might work now, but might fail on a different compiler.

In your case, apparently <iostream> includes <string> , directly or indirectly, but don’t rely on it.

Visual Studio 19 probably uses a more advanced C++ compiler where string is already included in iostream.

[mortalwombat]

Thanks.