Difference between iostream and iostream.h

Question

What is the difference between iostream and iostream.h?

Answer 1

iostream.h is deprecated by those compilers that provide it, iostream is part of the C++ standard.

To clarify explicitly there is no mention of iostream.h at all in the current C++ standard (INCITS ISO IEC 14882 2003).

Edit: As @Jerry mentioned, not only does the current standard not mention it, but no standard for C++ mentions it.

Answer 2

iostream is a standard header. iostream.h is a non-standard header that was very common in pre-standard C++, and is what iostream evolved from. It's still common to have iostream.h around, presumably for use with older programs.

If your implementation have a working copy of iostream.h, it is probably the same as iostream except that everything in iostream is in the std namespace, while iostream.h generally preceded namespaces, and didn't use them.

If your implementation has both iostream and iostream.h, iostream is likely to work like:

namespace std { #include <iostream.h> } 

although that's not necessarily how it's written.