Is using .h as a header for a c++ file wrong?

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+2 Q:

Is using .h as a header for a c++ file wrong?

I see it all over the place, especially with code written in the "C style". I noticed that Emacs always selects C highlighting style for a .h header, but c++ for hpp or hh.

Is it actually "wrong" to label your headers .h or is it just something which annoys me?

EDIT:

There is a good (ish) reason why this annoys me, if I have project files labelled, 'hpp & cpp' I can get away with 'grep something *pp' etc. otherwise I have to type '.h cpp'

+2 A:

It's like with the other files - .c for C, .cpp for C++ - use .h for C, .hpp for C++. This will satisfy most compilers/editors. It's not really wrong to not do so, but it can be used to give a hint which of the both languages you are actually using.

If you want to stop that behaviour without renaming the files, you should have a look at the Emacs config and try to change the source code detection.

schnaader 2009-03-17 13:25:19

+13 A:

nothing wrong with that. This is the default with Microsoft Visual C++.

Just follow the standard you like, and stick with it.

decasteljau 2009-03-17 13:25:24

And noting most of the standard library does not use an extension at all.

Richard 2009-03-17 13:31:09

The standard library is a special case though. Don't start writing headers with no extensions.

jalf 2009-03-17 13:43:20

The standard library headers aren't required to be "files" at all, so they aren't a good example here. The compiler is free to implement them as it sees fit.

Brian Neal 2009-03-17 17:26:26

I might have know it was all Bill's fault, grrrr

Chris Huang-Leaver 2009-03-18 08:52:53

+2 A:

Since Emacs has no easy way of finding out whether a .h file is C or C++, it's not ridiculous to choose C for .h files and C++ for .hpp files.

Note that all boost header files are suffixed with .hpp.

Benoît 2009-03-17 13:32:09

strange that vim doesn't have this problem, then?

anon 2009-03-17 13:46:35

Score one for the vim homers!

Judge Maygarden 2009-03-17 13:54:07

Heh, I recently decided to write some elisp bound to F9 to switch between c-mode and c++-mode exactly for .h header files:(defun switch-c-or-c++-mode () "Switch to c++-mode if currently c-mode, and vice-versa." (interactive) (cond ((eq major-mode 'c-mode) (c++-mode)) ((eq major-mode 'c++-mode) (c-mode))))

Paul Stephenson 2009-07-07 10:52:19

I suppose the real question is why would you want to make things needlessly more unclear.

Chris Huang-Leaver 2009-08-06 22:54:52

+4 A:

It's not wrong to call your C++ headers .h. There are no rules of what extensions your code must use. For your non-headers, MSVC uses .cpp and on Linux, .cc as well. There is no one global standard.

But I'd say calling your headers .hpp (I've seen .hh a few times as well) is a lot more consistent and informative than just using .h.

jalf 2009-03-17 13:45:11

+3 A:

You're free to use .h, .H, .hpp, .hxx, .hh, or whathaveyou. Just like you're free to use .c for C sources, and .C, .cpp, .cc, or .cxx for C++ sources. The extension is largely a convention.

greyfade 2009-03-17 17:31:03

ansaurus

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Is using .h as a header for a c++ file wrong?

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