Project Euler 22

I'm having a bit of an issue with my solution to Euler problem 22. I have a list of names that are surrounded by quotation makes and separated by commas (I.E. "MARY",). I have created a function (called format) which removes the quotation marks and commas and builds a new array with the names, delimiting them with line feeds (I.E. MARY\n). When I try printing this list with puts(), I get a formatted list as expected, but at the end all of the unformatted names also appear. Obviously, I would like to have only the formatted list returned. If anybody could offer some advice, I would be obliged.

Code:

---

/* Project Euler problem 22
 *
 * http://projecteuler.net/problem=22
 */

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

#define MAX_NAMES        6000

void alpha_sort(char *buff)
{
        const char alpha[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char *p;
        int i;

        // array of char pointers
        char *names[MAX_NAMES];
        /*names[0] = "test";*/
        /*p = names[0];*/
        /*printf("%c\n", p[0]);*/


}

char *format(char *buff)
{
        int i = 1, j = 0;
        char *p;
              p = malloc(sizeof(buff));

        while(buff[i] != '\0')
        {
                if(isalpha(buff[i]))
                {
                        p[j] = buff[i];
                        j++;
                        i++;
                }

                else
                {
                        p[j] = '\n';
                        j++;
                        do
                        {
                                i++;
                        } while ( (isalpha(buff[i]) == 0) && (buff[i] != '\0') );
                }
        }

        free(buff);

        return p;
}


char *rfile(void)
{
        long size = 0;
        FILE *fp;
        fp = fopen("names.txt", "r");
        fseek(fp, 0, SEEK_END);
        size = ftell(fp);

        // allocate memory size of file
        char *buff = (char*) malloc(sizeof(char) * size);

        rewind(fp);
        fread(buff, 1, size, fp);
        fclose(fp);

        return buff;
}

int main(void)
{
        char *p = format(rfile());
        puts(p);

        alpha_sort(p);

        return 0;
}

---

> char *buff = (char*) malloc(sizeof(char) * size);
This doesn't allow for adding a nul character at the end to mark the end of the string.

> fread(buff, 1, size, fp);
This won't add the nul character.

> char *p;
> p = malloc(sizeof(buff));
Do you know the difference between sizeof() and strlen() ?

My guess is you tried strlen() first, but it blew up because of the nul missing problem, so you tried sizeof() instead and got garbage results.