Thread: error: `O_CREAT' undeclared (first use in this function)

I'm have the compile error

Code:

error: `O_CREAT' undeclared (first use in this function)

in the line

Code:

start_bets[i] = sem_open(nome,O_CREAT|O_EXCL,0777,0);

even though I have done

Code:

#include <semaphore.h>

What other problems could generate this error?

Thanks for any help

I tried that and get even worse errors. It stops recognizing sem_open althogether.

Code:

/tmp/ccOHDxUk.o(.text+0x59): In function `main':
: undefined reference to `pthread_create'
/tmp/ccOHDxUk.o(.text+0x101): In function `main':
: undefined reference to `pthread_join'
/tmp/ccOHDxUk.o(.text+0x3a0): In function `init':
: undefined reference to `sem_unlink'
/tmp/ccOHDxUk.o(.text+0x3ba): In function `init':
: undefined reference to `sem_open'
/tmp/ccOHDxUk.o(.text+0x46e): In function `init':
: undefined reference to `sem_unlink'
/tmp/ccOHDxUk.o(.text+0x488): In function `init':
: undefined reference to `sem_open'
/tmp/ccOHDxUk.o(.text+0x4d8): In function `init':
: undefined reference to `sem_unlink'
/tmp/ccOHDxUk.o(.text+0x4fa): In function `init':
: undefined reference to `sem_open'
/tmp/ccOHDxUk.o(.text+0x5b1): In function `end_clean':
: undefined reference to `sem_unlink'
/tmp/ccOHDxUk.o(.text+0x63d): In function `end_clean':
: undefined reference to `sem_unlink'
/tmp/ccOHDxUk.o(.text+0x678): In function `end_clean':
: undefined reference to `sem_unlink'

If O_CREAT isn't in semaphore.h why doesn't on the man pages say so?

You need semaphore.h AND fcntl.h.

If I include both I get those errors I mentioned.

Here is a sample code that has the same prob

Code:

#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>

sem_t* start_race;

int main(void){
	sem_unlink("start_race"); //remove se já  existir
	if (SEM_FAILED != start_race){
		//sem_setvalue(start_race, 0, 0);
		start_race = sem_open("start_race",O_CREAT|O_EXCL,0777,0);
	}
	else{
		printf("Erro ao criar o semaforo start_race.\n");
		exit(0);
	}
}

Like that I get

Code:

namedSemaphores.c: In function `main':
namedSemaphores.c:11: error: `O_CREAT' undeclared (first use in this function)
namedSemaphores.c:11: error: (Each undeclared identifier is reported only once
namedSemaphores.c:11: error: for each function it appears in.)
namedSemaphores.c:11: error: `O_EXCL' undeclared (first use in this function)

With fcntl.h I get

Code:

/tmp/ccAx0hpm.o(.text+0x25): In function `main':
: undefined reference to `sem_unlink'
/tmp/ccAx0hpm.o(.text+0x47): In function `main':
: undefined reference to `sem_open'
collect2: ld returned 1 exit status

Please help! I don't know what more to do!

Did you try reading any of the replies?

Code:

#include <semaphore.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>

sem_t* start_race;

int main(void){
	sem_unlink("start_race"); //remove se já  existir
	if (SEM_FAILED != start_race){
		//sem_setvalue(start_race, 0, 0);
		start_race = sem_open("start_race",O_CREAT|O_EXCL,0777,0);
	}
	else{
		printf("Erro ao criar o semaforo start_race.\n");
		exit(0);
	}
}

Both.

That what I'm doing!

Look, with the code

Code:

#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

sem_t* start_race;

int main(void){
	sem_unlink("start_race"); //remove se já  existir
	if (SEM_FAILED != start_race){
		//sem_setvalue(start_race, 0, 0);
		start_race = sem_open("start_race",O_CREAT|O_EXCL,0777,0);
	}
	else{
		printf("Erro ao criar o semaforo start_race.\n");
		exit(0);
	}
}

I get

Code:

/tmp/ccgdq412.o(.text+0x25): In function `main':
: undefined reference to `sem_unlink'
/tmp/ccgdq412.o(.text+0x47): In function `main':
: undefined reference to `sem_open'
collect2: ld returned 1 exit status

Maybe I'm missing something of what you said, but that code is as far as I understood from reading the posts.

It compiles fine here. sem_open is a system call, at least in BSD. What system are you on?

I'm compiling on a server, so I'm not sure.
Is there a command for asking the system version?

Ok with uname I got

Code:

Linux student2.dei.uc.pt 2.6.11-1.27_FC3smp #1 SMP Tue May 17 20:43:11 EDT 2005 i686 i686 i386 GNU/Linux

Is that what you need?

I'm compiling with the command

Code:

 gcc -Wall -std=c99 namedSemaphores.c -o namedSemaphores

Not sure if this is what you asked

According to linux "man sem_overview":

Linking
Programs using the POSIX semaphores API must be compiled with cc -lrt to link against the real-time library, librt.

YOU ARE LIFESAVERS!

Thank you so very much!!