qsort : qsort « stdlib.h « C Tutorial

1. C Tutorial
2. stdlib.h
3. qsort

The function pointed to by compare is used to compare two elements of the array.

The form of the compare function must be as follows:

int func_name(const void *arg1, const void *arg2);

It must return values as described here:

The array is sorted into ascending order with the lowest address containing the lowest element.

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

  int num[10] = {
    1, 3, 6, 5, 8, 7, 9, 6, 2, 0
  };

  int comp(const void *, const void *);

  int main(void)
  {
    int i;

    printf("Original array: ");
    for(i=0; i<10; i++) printf("%d ", num[i]);

    qsort(num, 10, sizeof(int), comp);

    printf("Sorted array: ");
    for(i=0; i<10; i++) printf("%d ", num[i]);

    return 0;
  }

  /* compare the integers */
  int comp(const void *i, const void *j)
  {
    return *(int *)i - *(int *)j;
  }

Original array: 1 3 6 5 8 7 9 6 2 0 Sorted array: 0 1 2 3 5 6 6 7 8 9