Thread: please help to understand how recursion works in the following program or function.

Quicksort algorithm where it asks the user to enter 10 integers and it calls quicksort function to sort the array and print all the integers in sorted order.

Code:

#include<stdio.h>
#define N 10


void quicksort(int a[],int low , int high);
int split(int a[], int low, int high);


int main(void)
{
int a[N], i;


printf("enter 10 no.:");


for(i=0;i<N;i++)
{scanf("%d", &a[i]);}


quicksort(a, 0,N-1);


printf("In sorted order:");
for(i=0;i<N;i++)
printf("%d  ", a[i]);


printf("\n");
return 0;




}


void quicksort(int a[], int low, int high)
{
int middle;


if(low>=high)
return;


middle=split(a,low,high);


quicksort(a,low,middle-1);
quicksort(a,middle+1,high);
}


int split(int a[], int low, int high)
{
    int part=a[low];
    for( ; ;)
    {


        while(low < high && part<=a[high])
        {
            high--;
        }
        if(low>=high)
            break;
        else
            a[low++]=a[high];




        while(low<high && a[low] <= part)
        {
            low++;
        }
        if(low>=high)
            break;
        a[high--]=a[low];


    }
    a[high]=part;
return high;


}

please explain the steps in details regarding how recursion takes place in quicksort function. i m confused..sorry

Code:

void quicksort(int a[], int low, int high)
{
int middle;


if(low>=high)
return;


middle=split(a,low,high);


quicksort(a,low,middle-1);
quicksort(a,middle+1,high);
}

thank you.

Okay,i will do accordingly.
Thanks Salem.