Writing within a loop

[tommyb05]

This code is supposed to run through a loop and write data to a file descriptor.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void format(int n, char *d, FILE *f);

int main()
{

char *d="written";
FILE *f;
int i, n=0;

for(i=0; i<=5; i++)
{

	format(n, d, f);

	fprintf(f, "stack #1, 15");
	fclose(f);

}

     return 0;

}

void format(int n, char *d, FILE *f)
{

char fm[16];

	n++;
	snprintf(fm, 16, "%s.%d.txt", d, n);
	f = fopen(fm, "w");

}

When I run this program I get a "segmentation fault" and I'm not sure why. I'm guessing it has to do with format().

How can I use format() to correctly write data to a fd?

Thanks!

[Brafil]

You haven't opened the file. While calling format you've just passed a _copy_ of f. Try this;

int main(void)
{
    ....
        format(n, d, &f);
    ....
}

void format(int n, char *d, FILE **f)
{
    ...
    *f = fopen(fm, "w");
}

[tommyb05]

Thank you very much, works perfectly!