Pointers to Functions bubble sort Program example 7 in C programming language

 Pointers to Functions bubble Program Example 7 : 



/*------------------- bubble7.c ------------------*/

/* Program bubble_7.c from PTRTUT10.HTM  6/10/97 */

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

#define MAX_BUF 256
long arr[10] = { 3,6,1,2,3,8,4,1,7,2};
char arr2[5][20] = {  "Mickey Mouse",
                      "Donald Duck",
                      "Minnie Mouse",
                      "Goofy",
                      "Ted Jensen" };

void bubble(void *p, int width, int N,
            int(*fptr)(const void *, const void *));
int compare_string(const void *m, const void *n);
int compare_long(const void *m, const void *n);

int main(void)
{
    int i;
    puts("\nBefore Sorting:\n");

    for (i = 0; i < 10; i++)               /* show the long ints */
    {
        printf("%ld ",arr[i]);
    }
    puts("\n");

    for (i = 0; i < 5; i++)                  /* show the strings */
    {
        printf("%s\n", arr2[i]);
    }
    bubble(arr, 4, 10, compare_long);          /* sort the longs */
    bubble(arr2, 20, 5, compare_string);     /* sort the strings */
    puts("\n\nAfter Sorting:\n");

    for (i = 0; i < 10; i++)             /* show the sorted longs */
    {
        printf("%d ",arr[i]);
    }
    puts("\n");

    for (i = 0; i < 5; i++)            /* show the sorted strings */
    {
        printf("%s\n", arr2[i]);
    }
    return 0;
}

void bubble(void *p, int width, int N,
            int(*fptr)(const void *, const void *))
{
    int i, j, k;
    unsigned char buf[MAX_BUF];
    unsigned char *bp = p;

    for (i = N-1; i >= 0; i--)
    {
        for (j = 1; j <= i; j++)
        {
            k = fptr((void *)(bp + width*(j-1)), (void *)(bp + j*width));
  if (k > 0)
            {
                memcpy(buf, bp + width*(j-1), width);
                memcpy(bp + width*(j-1), bp + j*width , width);
                memcpy(bp + j*width, buf, width);
            }
        }
    }
}

int compare_string(const void *m, const void *n)
{
    char *m1 = (char *)m;
    char *n1 = (char *)n;
    return (strcmp(m1,n1));
}

int compare_long(const void *m, const void *n)
{
    long *m1, *n1;
    m1 = (long *)m;
    n1 = (long *)n;
    return (*m1 > *n1);
}

/*----------------- end of bubble7.c -----------------*/