The C Programming Language

Sorting Example Program

 /* Using qsort() and bsearch() with values.*/

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

 #define MAX 20

 int intcmp(const void *v1, const void *v2);

 main()
 {
     int arr[MAX], count, key, *ptr;

     /* Enter some integers from the user. */

     printf("Enter %d integer values; press Enter after each.\n", MAX);

     for (count = 0; count < MAX; count++)
         scanf("%d", &arr[count]);

     puts("Press a key to sort the values.");
     getch();

     /* Sort the array into ascending order. */

     qsort(arr, MAX, sizeof(arr[0]), intcmp);

     /* Display the sorted array. */

     for (count = 0; count < MAX; count++)
         printf("\narr[%d] = %d.", count, arr[count]);

     puts("\nPress a key to continue.");
     getch();

     /* Enter a search key. */

     printf("Enter a value to search for: ");
     scanf("%d", &key);

     /* Perform the search. */

     ptr = (int *)bsearch(&key, arr, MAX, sizeof(arr[0]),intcmp);

     if ( ptr != NULL )
         printf("%d found at arr[%d].", key, (ptr - arr));
     else
         printf("%d not found.", key);
 }

 int intcmp(const void *v1, const void *v2)
 {
     return (*(int *)v1 - *(int *)v2);
 }