timespec not found in time.h

Question

I am having to rewrite an application from C++ to C. I am using gcc and Eclipse on Ubuntu 12.04. In doing so I have come across this error

../src/TTNoddy.c: In function ‘main’:
../src/TTNoddy.c:16:2: error: unknown type name ‘timespec’

Here is my code snippet that reproduces the problem

#include <time.h>

int main(void) {

    timespec TS;
    TS.tv_nsec = 1;

    return 0;
}

I am confused here - I am a C++ coder and never written a pure C application in my life, but the man page for clock_gettime clearly indicates that timespec is found in the time.h header file which I am including here. What have I missed?

score 23 · Accepted Answer · edited Dec 18 '13 at 12:17

23

timespec is a struct, you need to explicitly tell the compiler this. If you carefully read the man page you can see it is stated so.

This should work:

#include <time.h>

int main(void) {
    struct timespec TS;
    TS.tv_nsec = 1;

    return 0;
}

Additional note: If it had been defined as a typedef struct, you would not have needed to add the struct part manually. But, you should assume that most/all pure C structs are not defined as a typedef

edited Dec 18 '13 at 12:17

Krizz

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answered Jun 22 '12 at 09:16

Veger

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Thanks. I knew it was a struct, it is just coming from C++ where my code works I never knew you had to explicitly declare each timespec with struct first. I guess there will be many differences that I am going to find like this. – mathematician1975 Jun 22 '12 at 09:24
2

Also note that timespec is not part of C89/C99 but POSIX. http://stackoverflow.com/questions/3875197/std-c99-wtf-on-linux – Morpfh Sep 22 '12 at 21:55
Actually my mingw32 compiler doesnt define timespec in time.h at all. But rather pthread.h – Mar 05 '20 at 19:09

score 3 · Answer 2 · answered Jun 22 '12 at 09:16

3

It should not be just timespec as timespec is a struct. It should be struct timespec. Please modify your code accordingly.

answered Jun 22 '12 at 09:16

Jay

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score 2 · Answer 3 · answered Nov 08 '15 at 10:37

I got this error when trying to compile a working project under Visual Studio 2015.

The solution was to add HAVE_STRUCT_TIMESPEC to the Preprocessor Definitions.

Through the GUI: Project Properties (pan) > Property Pages (icon) > Configuration Properties > C/C++ > Preprocessor > Preprocessor Definitions > Edit > Add HAVE_STRUCT_TIMESPEC

Or manually: Edit each project file and replace each instance of <PreprocessorDefinitions> (there can be several per file) with something like:

<PreprocessorDefinitions>HAVE_STRUCT_TIMESPEC;WIN32;__GNU_LIBRARY__;_DEBUG;_CONSOLE;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>

NB: I found this answer somewhere on a Github issue, so I'm posting it here.

Also see [Timespec redefinition error](http://stackoverflow.com/q/33557506) and [Timespec :struct type Error c2011](http://stackoverflow.com/q/33114535). — jww, Aug 14 '16 at 06:02

score 2 · Answer 4 · answered Mar 18 '19 at 06:13

2

This issue gave me problems for a while, what I ended up doing was defining struct timespec in my code. (just copied it over, straight from man nanosleep)

#include <time.h>

struct timespec {
    time_t tv_sec;        /* seconds */
    long   tv_nsec;       /* nanoseconds */
};

int main(void) {
    struct timespec TS;
    TS.tv_nsec = 1;

    return 0;
}

answered Mar 18 '19 at 06:13

gilbert

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Wrap it in a namespace and it will be elegant as much as possible. – Mikolasan Jan 02 '20 at 06:28

score 2 · Answer 5 · answered Sep 18 '19 at 15:56

2

I know this is an old question but I was having the same problem after upgrading from gcc 6.3 to 7.1. After looking at the changes you have to define _GNU_SOURCE to include struct_timespec.h.

answered Sep 18 '19 at 15:56

Mike Seeds

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timespec not found in time.h

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