What is the différence between #include <iostream.h> and #include <iostream>?

Question

What is the difference between

#include <iostream.h>

and

#include <iostream>

?

Answer 1

Before C++ was even standardised, the I/O library was developed as <iostream.h>. However, that header has never been a standard C++ header. Some older compilers continued to distribute the <iostream> header also as <iostream.h>. Use <iostream> because it is guaranteed by the standard to exist.

It's worth noting that the only standard headers that end with .h are the C standard library headers. All C++ standard library headers do not end with .h.