Is include needed for FILE in C?

Question

I have a header file (sample.h) for my c file (sample.c). When I prototyped a function in my header file as below.

return_type sample_fun (FILE *filePtr);

I get a compilation error saying, Syntax error: possible missing ')' or ','? When I include the stdio.h error is resolved. Is the stdio.h include mandatory? Some of my files work well without the include.

I use gcc on AIX.

Which files work well without it? Probably, those files include some other header which includes stdio.h. — William Pursell, Apr 30 '11 at 12:29
@Will Yes, they might as they include a lot of header files. — San, May 02 '11 at 09:51

score 5 · Accepted Answer · answered Apr 30 '11 at 12:27

5

Yes, the type FILE is defined in stdio.h; if you mention it, then you must include that file.

answered Apr 30 '11 at 12:27

Ernest Friedman-Hill

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score 2 · Answer 2 · edited May 23 '17 at 12:19

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Yes it is. FILE is typedefed from a struct iobuf on most platforms. This requires that the full definition of struct iobuf be present, even though all the interfaces use FILE *, and pointer types do not normally require full definitions prior to their use (C limitation).

See this question for more information: Forward declare FILE *

edited May 23 '17 at 12:19

Community

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answered Apr 30 '11 at 12:28

Matt Joiner

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Is include needed for FILE in C?

2 Answers2