C++ Array Sorting Function

6 min read Jul 05, 2024

C++ Array Sorting Functions

Sorting arrays is a fundamental task in programming. C++ provides a variety of built-in functions and algorithms for efficient array sorting. Let's explore some of the most common methods:

1. `std::sort` from `<algorithm>`

The std::sort function from the <algorithm> header is a powerful and versatile sorting algorithm. It uses the IntroSort algorithm, a hybrid approach that combines the efficiency of quicksort with the stability of heapsort. Here's how to use it:

#include 
#include 

int main() {
  int arr[] = {5, 2, 9, 1, 5};
  int n = sizeof(arr) / sizeof(arr[0]);

  std::sort(arr, arr + n); 

  std::cout << "Sorted array: ";
  for (int i = 0; i < n; i++) {
    std::cout << arr[i] << " ";
  }
  std::cout << std::endl;

  return 0;
}

Explanation:

std::sort(arr, arr + n): Sorts the array arr from the starting element arr to the element arr + n.
n: Number of elements in the array.

2. `std::stable_sort` from `<algorithm>`

The std::stable_sort function is similar to std::sort but ensures that elements with the same value maintain their relative order after sorting. It uses a MergeSort algorithm, which is known for its stability.

#include 
#include 

int main() {
  int arr[] = {5, 2, 9, 1, 5};
  int n = sizeof(arr) / sizeof(arr[0]);

  std::stable_sort(arr, arr + n); 

  std::cout << "Sorted array: ";
  for (int i = 0; i < n; i++) {
    std::cout << arr[i] << " ";
  }
  std::cout << std::endl;

  return 0;
}

3. Custom Sorting using `std::sort` with a Comparison Function

You can customize the sorting behavior of std::sort by providing a comparison function. This allows you to sort based on specific criteria.

#include 
#include 

bool compare(const int& a, const int& b) {
  return a > b; // Sort in descending order
}

int main() {
  int arr[] = {5, 2, 9, 1, 5};
  int n = sizeof(arr) / sizeof(arr[0]);

  std::sort(arr, arr + n, compare); 

  std::cout << "Sorted array: ";
  for (int i = 0; i < n; i++) {
    std::cout << arr[i] << " ";
  }
  std::cout << std::endl;

  return 0;
}

Explanation:

compare function: Defines the sorting logic. In this example, it sorts in descending order.

4. Bubble Sort (Manually Implemented)

Bubble Sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order. It's not very efficient for large datasets but can be helpful for understanding basic sorting concepts.

#include 

void bubbleSort(int arr[], int n) {
  for (int i = 0; i < n - 1; i++) {
    for (int j = 0; j < n - i - 1; j++) {
      if (arr[j] > arr[j + 1]) {
        std::swap(arr[j], arr[j + 1]);
      }
    }
  }
}

int main() {
  int arr[] = {5, 2, 9, 1, 5};
  int n = sizeof(arr) / sizeof(arr[0]);

  bubbleSort(arr, n);

  std::cout << "Sorted array: ";
  for (int i = 0; i < n; i++) {
    std::cout << arr[i] << " ";
  }
  std::cout << std::endl;

  return 0;
}

Important Considerations:

Performance: For optimal efficiency, use std::sort or std::stable_sort for general sorting tasks. They are highly optimized and provide the best performance.
Custom Sorting: If you require specialized sorting criteria, create a comparison function and use it with std::sort.
Data Types: The sorting functions can be used with various data types (int, float, string, etc.) and can be adapted to work with user-defined data structures.

By understanding these C++ array sorting functions, you can efficiently and effectively sort data in your programs.

C++ Array Sorting Function