You want to include iostream
. iostream.h
was present in Stroustrup's C++:
The original iostream library was written to challenge the claim that
a terse, type safe I/O system needed special language support. 1 It
was developed at Bell Labs by Bjarne Stroustrup and shipped with the
original C++ compiler, CFront and described in the first edition of
Stroustrup's The C++ Programming Language. This version of the
iostream library lived in the headers iostream.h, fstream.h and so on.
The Standard C++ has the headers without the .h, so you want to:
#include <iostream>
Here is an article that discusses this.