implicit declaration of function ‘close’

Hi,
I wrote a simple piece of code as an exercise in file_descriptors which opens a file and then closes it using open and close. When I try to compile it using the flags -Wall -ansi -Werror with gcc, the get this error.

implicit declaration of function ‘close’

heres the code.

Code:

---

/* sample code to open and close a file using file descriptors */

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

int main(){

        int file_descriptor,error_code;
        char filename[] = "sample_text.txt";

        file_descriptor = open(filename, O_WRONLY | O_CREAT | O_EXCL);

        if(file_descriptor == -1) {
                perror("cannot open file\n");
                exit(1);
                }

        /* close the opened file */
        error_code = close(file_descriptor);

        if(error_code == -1){
                perror("cannot close file\n");
                exit(1);
                }

        return 0;
}

---

Can anyone throw some hint?

-Livin

The close() system call is declared in unistd.h, which you have not included. That's why you get a warning about implicit declaration.

Oddly, close is in another header file to open

Quote:

---

NAME
close - close a file descriptor

SYNOPSIS
#include <unistd.h>

int close(int fd);

---

But unistd does have read/write/seek as well, so that's the end of the weirdness.

oh ok. I included the unistd.h and it worked. thanks you two!