Convert a set to a vector in C++

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

1. Using Range Constructor

The most elegant solution is to use the std::vector range constructor, which takes two input iterators pointing to the beginning and the end of an input sequence.

#include <iostream>

#include <set>

#include <vector>

#include <algorithm>

int main()

{

std::set<char> s = { 'a', 'b', 'c', 'd', 'e' };

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

for (char const &c: v) {

std::cout << c << ' ';

}

return 0;

}

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Output:

a b c d e

2. Using `std::copy` function

Another good alternative is to use the std::copy, which inserts elements from a source container into a destination container. The destination container should be large enough to accommodate all elements.

#include <iostream>

#include <set>

#include <vector>

#include <algorithm>

int main()

{

std::set<char> s = { 'a', 'b', 'c', 'd', 'e' };

std::vector<char> v(s.size());

std::copy(s.begin(), s.end(), v.begin());

for (char const &c: v) {

std::cout << c << ' ';

}

return 0;

}

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Output:

a b c d e

We can also pass a std::back_inserter to std::copy. This works fine on an empty container as it creates an output iterator that calls push_back on the destination container for each array element.

#include <iostream>

#include <set>

#include <vector>

#include <algorithm>

int main()

{

std::set<char> s = { 'a', 'b', 'c', 'd', 'e' };

std::vector<char> v;

std::copy(s.begin(), s.end(), std::back_inserter(v));

for (char const &c: v) {

std::cout << c << ' ';

}

return 0;

}

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Output:

a b c d e

3. Using `std::vector::assign` function

One can also use vector::assign that replaces the current contents of the vector with each of the elements in the specified range.

#include <iostream>

#include <set>

#include <vector>

#include <algorithm>

int main()

{

std::set<char> s = { 'a', 'b', 'c', 'd', 'e' };

std::vector<char> v;

v.assign(s.begin(), s.end());

for (char const &c: v) {

std::cout << c << ' ';

}

return 0;

}

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Output:

a b c d e

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

Convert a set to a vector in C++

1. Using Range Constructor

2. Using std::copy function

3. Using std::vector::assign function

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2. Using `std::copy` function

3. Using `std::vector::assign` function