Create file with fixed length and initiate it to all 0's

Hi all,

Is there a good way to create a new file with 1024 bytes, and initiate it to all 0's ?

Thank you...

Hmm I'm assuming you want the file of size 1024 bytes with all zeros in it, so you may be looking at:

Code:

---

#include <stdio.h>

#define SIZE 1024

int main(int argc, char **argv)
{
        FILE *fp = fopen("sample.txt","w");
        int i = 0, c = 0;

        if (fp == NULL) {
                fprintf(stderr,"Could not open for writing!\n");
                exit(1);
        }

        for (i = 0; i < SIZE; i++)
        {
                c = fputc("0",fp);
                if (c == EOF)
                        fprintf(stderr,"Error!\n");
        }

        if(fclose(fp) != 0)
        {
                fprintf(stderr,"Could not close properly!\n");
                exit(1);
        }

        return 0;
}

---

I must admit looks pretty horrible and I'm pretty sure someone has a neater solution :)

If you mean 0 as in character '0'...

Code:

---

  char bytes[1024];
  for( int i=0; i<1024; ++i )
    bytes[i] = '0';
  fwrite( bytes, 1, 1024, f );

---

Or 0 as in binary 0...

Code:

---

  char bytes[1024] = {0};
  fwrite( bytes, 1, 1024, f );

---

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(void)
{
  char *filename = "slappy.dat";
  char fill[1024];
  int fd;

  memset(fill, '0', sizeof(fill));

  if((fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT,
    S_IRUSR | S_IWUSR)) == -1)
  {
    puts("Error opening file for writing!");
    exit(1);
  }

  if(write(fd, fill, sizeof(fill)) != sizeof(fill))
    puts("Error writing to file!");

  close(fd);
  return 0;
}

---

Quote:

---

itsme@itsme:~/C$ cat slappy.dat
00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 000000000000000000000000itsme@itsme:~/C$

---

EDIT: Don't ask me why it looks like the 0's are in 2 columns...the forum is doing that for some reason. The 0's are actually all adjacent to each other in my output file.

Quote:

---

Originally Posted by 0rion

Code:

---

                c = fputc("0",fp);

---

I must admit looks pretty horrible and I'm pretty sure someone has a neater solution :)

---

Indeed it does. You see, fputc doesn't take a string as an argument. ;)

Quzah.