Transform a vector to a set in C++

This post will discuss how to transform a vector to a set in C++.

A simple solution to transform a vector to a set is using the std::set range constructor. It can accept iterator to the initial and final positions of a vector and constructs a set container with elements of the range. The following program demonstrates this:

#include <iostream>

#include <vector>

#include <set>

int main()

{

std::vector<char> v = { 'A', 'B', 'C', 'D' };

std::set<char> s(v.begin(), v.end());

for (const auto &val: s) {

std::cout << val << ' ';

}

return 0;

}

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Output:

A B C D

The above solution copies all elements from a vector to a set. Instead of copying each element, we can actually move each element from a vector to a set using the move iterator std::make_move_iterator, available with C++11.

#include <iostream>

#include <vector>

#include <set>

int main()

{

std::vector<char> v = { 'A', 'B', 'C', 'D' };

std::set<char> s(std::make_move_iterator(v.begin()), std::make_move_iterator(v.end()));

// vector now contains unspecified values; clear it:

v.clear();

for (const auto &val: s) {

std::cout << val << ' ';

}

return 0;

}

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Output:

A B C D

We can also write custom logic for transforming a vector into a set. Here’s what the code would look like:

#include <iostream>

#include <vector>

#include <set>

int main()

{

std::vector<char> v = { 'A', 'B', 'C', 'D' };

std::set<char> s;

for (const auto &i: v) {

s.insert(i);

}

for (const auto &i: s) {

std::cout << i << ' ';

}

return 0;

}

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Output:

A B C D

That’s all about transforming a vector to a set in C++.

Transform a vector to a set in C++

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