Program for quick sort with time complexity

Program
Time Complexity: O(n²)

#include <stdio.h>
#include <conio.h>
#include <time.h>
void Exch(int *p, int *q)
{
    int temp = *p;
    *p = *q;
    *q = temp;
}
void QuickSort(int a[], int low, int high)
{
    int i, j, key, k;
    if (low >= high)
        return;
    key = low;
    i = low + 1;
    j = high;
    while (i <= j)
    {
        while (a[i] <= a[key])
            i = i + 1;
        while (a[j] > a[key])
            j = j - 1;
        if (i < j)
            Exch(&a[i], &a[j]);
    }
    Exch(&a[j], &a[key]);
    QuickSort(a, low, j - 1);
    QuickSort(a, j + 1, high);
}
void main()
{
    int n, a[1000], i;
    clock_t st, et;
    double ts;
    printf("*********************************************************");
    printf("\n*********************************************************");
    printf("\n**    WAP for quick sort with time complexity in C     **");
    printf("\n**                Created by Sheetal Garg              **");
    printf("\n**                 Assistant Professor                 **");
    printf("\n**                 Phone No:9467863365                 **");
    printf("\n*********************************************************");
    printf("\n*********************************************************");
    printf("\n Enter How many Numbers: ");
    scanf("%d", &n);
    printf("\nEnter array elements\n");
    for (i = 0; i < n; i++)
        scanf("%d", &a[i]);
    st = clock();
    QuickSort(a, 0, n - 1);
    et = clock();
    ts = (double)(et - st) / CLOCKS_PER_SEC;
    printf("\nSorted Numbers are: \n");
    for (i = 0; i < n; i++)
        printf("%d\n", a[i]);
    printf("\nThe time taken is %e", ts);
}

Output 1

*********************************************************
*********************************************************
**    WAP for quick sort with time complexity in C     **
**                Created by Sheetal Garg              **
**                 Assistant Professor                 **
**                 Phone No:9467863365                 **
*********************************************************
*********************************************************
 Enter How many Numbers: 8

Enter array elements
23
32
21
14
21
23
43
31

Sorted Numbers are:
14     
21      
21      
23      
23
31      
32      
43
The time taken is 0.000000e+000