quicksort problem

#include <stdio.h>

void quickSort(int a[], int l, int r){
    int k = partition(a, l, r);
    if(r <= l){
        return;
    }
    quickSort(a, l, k-1);
    quickSort(a, k+1, r);
}

int partition(int a[], int l, int r){
    int i,j,k,v;
    k = r;
    v = a[k];
    i = l;
    j = r-1;
    int hold = -1;

    while(1){
        while(i < r && a[i] <= v){
            i++;
        }
        while(j >= l && a[j] >= v){
            j--;
        }
        if(i >= j){
            break;
        }else{
            hold = a[i];
            a[i] = a[j];
            a[j] = hold;
        }
    }
    hold = a[k];
    a[k] = a[i];
    a[i] = hold;
//
//    printf("\n\n\n\n");
//
//    for(int u = 0; u < 20; u++){
//        printf("%d\n", a[u]);
//    }

    printf("\n\n\n k: %d \n\n\n", i);

    return i;
}

int main(){
    //array that has to be sorted
    int a[20];

    //filling the array with random numbers between 0 and 100 without doubling
    for(int i = 0; i < 20; i++){
        int z;
        while(1){
            z = rand();
            int boolean = 0;
            if(z < 0){
                z = (-1) * z;
            }
            if(z > 200){
                boolean = 1;
            }
            for(int j = 0; j <= i; j++){
                if(a[j] == z){
                    boolean = 1;
                }
            }
            if(boolean == 0){
                break;
            }
        }
        a[i] = z;
    }



    //printing out the array to be able to check later
    for(int j = 0; j < 20; j++){
        printf("%d\n", a[j]);
    }
    printf("\nsorted array now:\n\n");

    //call quickSort
    quickSort(a, 0, 19);

     printf("\n\n\n");

    //printing out sorted array
    for(int j = 0; j < 20; j++){
        printf("%d\n", a[j]);
    }

    return 0;
}