What is the difference between including iostream and including iostream.h?

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Difference between iostream and iostream.h

My professor said that the following:

#include <iostream.h>

is the same as:

#include <iostream>
using namespace std;

I'm a bit confused. What is the difference between iostream and iostream.h?

Your professor needs to get out of 1988 and join the rest of us. — WhozCraig, Jan 17 '13 at 22:50
Many of the standard C header files (such as ``) have a C++ equivalent (such as ``) which wraps the C functions in `namespace std`, but `iostream` is not one of them. — Adam Rosenfield, Jan 17 '13 at 22:51
To be crystal clear on this point: **your professor is wrong**. Might be worth pondering on what else he's been wrong about. — Lightness Races in Orbit, Jan 18 '13 at 00:04

score 8 · Accepted Answer · edited Jan 17 '13 at 23:04

iostream.h is not part of the standard C++ library whereas iostream is. Names in iostream.h are not in the std namespace, whereas those in iostream are. By issuing the directive using namespace std after including iostream, all names defined there (and in any other standard library includes) are brought into the global namespace. That is usually not a good thing, but it does provide some level of equivalence between the standard and non- or pre-standard versions.

As far as claiming that they are "the same" as each other, this is unlikely. iostream adheres to the standard, and will have evolved w.r.t. iostream.h. This is particularly true if you consider the C++11 standard.

lethal-guitar · Answer 2 · 2013-01-17T22:57:03.370

1

Some very old compilers have used iostream.h, but it's not part of the standard. Only the extensionless header files are. It won't even be recognized by modern standard-compliant compilers.

edited Jan 17 '13 at 22:57

answered Jan 17 '13 at 22:50

lethal-guitar

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What is the difference between including iostream and including iostream.h?

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