A new start, with QuickSort Algorithm

Writing a blog is totally new for me. I would try to document my thoughts and ideas during learning or working (on projects mostly). At first it would be like a diary, just a note of what I have done recently. Hopefully, I can one day write down something more valuable and inspiring.

Today it is just the process of implementing QuickSort. Following is my code and I have commentted where I made a mistake.

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

int ChoosePivot(int l, int r){
    int randNum = rand();
    int pivotIndex;
    pivotIndex = randNum %(r-l+1);
    pivotIndex = pivotIndex + l;
    return pivotIndex;
}

int PartitionAroundPivot(int* A, int pivotIndex, int l, int r){
    int i,j;
    int pivot = A[pivotIndex], temp;

    i = l + 1;
    j = l;
    //swap pivot to the first one
    if (pivotIndex != l){
        temp = A[l]; A[l] = A[pivotIndex]; A[pivotIndex] = temp;
    }
    for (j = l + 1; j < r + 1; j++){
        if (A[j] < pivot) {
            temp = A[i]; A[i] = A[j]; A[j] = temp;
            i++;
        }
    }
    temp = A[i-1]; A[i-1] = pivot; A[l] = temp; //should swap A[i-1] instead of A[i];
    return i-1;

}

void QuickSort(int* A, int l, int r){
    int i;
    if (l<r){
        int pivotIndex,pivotPos;
        pivotIndex = ChoosePivot(l,r); //return the index of the pivot
        pivotPos = PartitionAroundPivot(A,pivotIndex,l,r);
        for (i=0;i<6;i++){
            printf("%d,",A[i]);
        }
        printf("\n");
        QuickSort(A,l,pivotPos-1);
        QuickSort(A,pivotPos+1,r);
    }
}


int main(){
    int A[6] = {5,1,5,3,5,6};
    int i = 0;
    QuickSort(A,0,5);
    for (i = 0; i < 6; i++){
        printf("%d,",A[i]);
    }
    printf("\n");
    return 0;
}

 In a more detailed manner,

temp = A[i-1]; A[i-1] = pivot; A[l] = temp; //should swap A[i-1] instead of A[i];

This is the swapping step after partitioning the elements that are not pivot. At this point, i points to the first element that is larger than pivot. Therefore, we should swap the one left of it with the pivot. A rather foolish mistake.

Futhermore, I am not quite sure if rand() function in C generates random number uniformly in the range [0, RAND_MAX]. I have done some searching on Stack Overflow and Quora but have not yet understood the problem. Here are some urls that may help.

https://www.quora.com/The-rand-function-in-the-standard-C-library-returns-a-uniformly-random-number-in-0-RAND_MAX-1-Does-rand-mod-n-generate-a-number-uniformly-distributed-0-n-1

http://stackoverflow.com/questions/11641629/generating-a-uniform-distribution-of-integers-in-c