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How to swap two elements in 1D array in C++

Sarah Tanveer

In this shot, we will learn how to swap two elements in a one-dimensional arraythe simplest form of array in C++. It is a group of elements that have the same datatype and same name..

Swapping 3 and 1

Code

Example 1: Manually swapping elements

In this algorithm, we use a temporary variable to swap the elements.

  1. The value of the first element (arr[0]) is stored in temp.

  2. The value of the second index (arr[2]) is then assigned to the first index (arr[0]).

  3. The value of temp is then assigned to the second index (arr[2]).

#include <iostream>
using namespace std;

// user defined function to print array
void printArr (int arr[], int size) {
    for(int i = 0; i < size; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;
}

int main() {

  // declare array
  const int size = 5;
  int arr[size] = {5, 2, 3, 4, 1};

  // temp variable to aid in swapping
  int temp;

  cout << "Original array: ";
  printArr(arr, size);

  // swapping first and last element
  temp = arr[0];
  arr[0] = arr[size - 1];
  arr[size - 1] = temp;

  cout << "Array with first and last element swapped: ";
  printArr(arr, size);

  return 0;
}

Example 2: Using std::swap() to swap elements

The built-in swap() function can swap two values in an array.


template <class T> void swap (T& a, T& b);

The swap() function takes two arguments of any data typethis specifies the type of data that a variable can store, such as integer, floating, or character, etc., i.e., the two values that need to be swapped.

Return value

This function returns nothing.

#include <iostream>
using namespace std;

// user defined ftn to print array
void printArr (int arr[], int size) {
    for(int i = 0; i < size; i++) {
        cout << arr[i] << " ";
    }
    cout << endl;
}

int main() {

  // declare array
  const int size = 5;
  int arr[size] = {5, 2, 3, 4, 1};

  // temp variable to aid in swapping
  int temp;

  cout << "Original array: ";
  printArr(arr, size);

  // swapping first and last element
  swap(arr[0], arr[size - 1]);

  cout << "Array with first and last element swapped: ";
  printArr(arr, size);

  return 0;
}

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