quicksort algorithm c code example

Example 1: quick sort program in c

#include<stdio.h>
void quicksort(int number[25],int first,int last){
   int i, j, pivot, temp;

   if(first<last){
      pivot=first;
      i=first;
      j=last;

      while(i<j){
         while(number[i]<=number[pivot]&&i<last)
            i++;
         while(number[j]>number[pivot])
            j--;
         if(i<j){
            temp=number[i];
            number[i]=number[j];
            number[j]=temp;
         }
      }

      temp=number[pivot];
      number[pivot]=number[j];
      number[j]=temp;
      quicksort(number,first,j-1);
      quicksort(number,j+1,last);

   }
}

int main(){
   int i, count, number[25];

   printf("How many elements are u going to enter?: ");
   scanf("%d",&count);

   printf("Enter %d elements: ", count);
   for(i=0;i<count;i++)
      scanf("%d",&number[i]);

   quicksort(number,0,count-1);

   printf("Order of Sorted elements: ");
   for(i=0;i<count;i++)
      printf(" %d",number[i]);

   return 0;
}

Example 2: quicksort in code

// A full c++ quicksort algorithm no bs
// quicksort in code

#include <iostream>

using namespace std;

void QuickSort(int arr[], int start, int end);
int Partition(int arr[], int start, int end);
void SwapArrMem(int arr[], int a, int b);

int main()
{

	int arr[4]; //change the size of the array to your desired array size

	cout << "enter " << sizeof(arr) / sizeof(arr[0]) << " numbers. press enter after input" << endl;

	for (int i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
	{
		
		cin >> arr[i];
	}

	cout << endl << "The sorted numbers are:" << endl << endl;



	QuickSort(arr, 0, sizeof(arr) / sizeof(arr[0]) - 1);

	for (int i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
	{
		cout << arr[i] << endl;
	}

}

void QuickSort(int arr[], int start, int end)
{
	if (start >= end) return;

	int index = Partition(arr, start, end);
	QuickSort(arr, start, index - 1);
	QuickSort(arr, index + 1, end);
}

int Partition(int arr[], int start, int end)
{
	int pivotindex = start;
	int pivotvalue = arr[end];
	for (int i = start; i < end; i++)
	{
		if (arr[i] < pivotvalue)
		{
			SwapArrMem(arr, i, pivotindex);
			pivotindex++;
		}
	}
	SwapArrMem(arr, pivotindex, end);
	return pivotindex;
}

void SwapArrMem(int arr[], int a, int b)
{
	int temp = arr[a];
	arr[a] = arr[b];
	arr[b] = temp;
}

Example 3: quicksort in c

int cmpfunc (const void * a, const void * b) {
   return ( *(int*)a - *(int*)b );
}