Using set_symmetric_difference in C++

The ‘set_symmetric_difference’ function in C++ is used to compare two sets and fill a container with their symmetric difference. The symmetric difference of two sets is the set of elements which are in either of the sets, but not in their intersection. In this article, we will explore how to use the ‘set_symmetric_difference’ function with an example.

Description

The ‘set_symmetric_difference’ function takes two input ranges, representing the two sets to be compared, and a destination range where the result will be stored. The input ranges must be sorted. The function fills the destination range with the elements that are in either of the input ranges but not in both.

Example

Here is an example demonstrating how to use ‘set_symmetric_difference’ in C++:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {

    // initialize arrays - must be sorted
    int firstArray[5] = { 0, 2, 4, 6, 8 };
    int secondArray[5] = { -4, -2 , 0, 2, 4 };

    // destination must be large enough to hold values
    std::vector<int> destination(10);
    std::vector<int>::iterator itr;

    // set iterator to start at new vector of differences
    itr = std::set_symmetric_difference(firstArray, firstArray + 5, secondArray, secondArray + 5, destination.begin());

    // trim non-value elements
    destination.resize(itr - destination.begin());

    // print vector of values
    std::cout << "The difference between the two sets is:";
    for (int i = 0; i < destination.size(); ++i) {
        std::cout << " " << destination[i];
    }

    return 0;
}

Explanation

In this example, we have two sorted arrays: ‘firstArray’ and ‘secondArray’. The ‘destination’ vector is used to store the result of the symmetric difference. The ‘set_symmetric_difference’ function compares the two arrays and fills the ‘destination’ vector with elements that are in either of the arrays but not in both.

After computing the symmetric difference, we resize the ‘destination’ vector to remove any unused elements. Finally, we print the elements of the ‘destination’ vector.

Use Case: Comparing Data Sets

A common use case for the ‘set_symmetric_difference’ function is comparing data sets to identify unique elements. For example, if you have two lists of user IDs from different systems and you want to find which users are unique to each system, you can use ‘set_symmetric_difference’ to obtain the result.

Wrapping It Up

The ‘set_symmetric_difference’ function is a powerful tool in C++ for comparing two sets and finding their symmetric difference. By understanding how to use this function, you can efficiently perform set operations and manage your data effectively.