QuickSort.c

#include <stdio.h>

void swap(int* a, int* b)
{
    int temp = *a;
    *a       = *b;
    *b       = temp;
}

int partition(int arr[], int low, int high)
{
    int pivot = arr[high];
    int     i = low - 1;
    
    for (int j = low; j < high; ++j)
    {
        if (arr[j] <= pivot)
        {
            i++;
            swap(&arr[i], &arr[j]);
        }
    }
    
    swap(&arr[i + 1], &arr[high]);
    
    return i + 1;
}

void sort(int arr[], int low, int high)
{
    if (low >= high || low < 0)
        return;
        
    int part = partition(arr, low, high);
    
    sort(arr, low, part - 1);
    sort(arr, part + 1, high);
}

int main()
{
    int arr[] = { 5, 2, 9, 3, 6, 1, 7 };
    
    sort(arr, 0, (*(&arr + 1) - arr) - 1);
    
    for (int i = 0; i < (*(&arr + 1) - arr); ++i)
        printf("%d ", arr[i]);
        
    return 0;
}