How to Insert a Range of Elements in a Set in C++ STL?

Prerequisites: Set in C++

Sets in C++ are a type of associative container in which each element has to be unique because the value of the element identifies it. The values are stored in a specific sorted order i.e. either ascending or descending.

Syntax:

set<datatype> set_name;

Some Basic Functions Associated with Set: 

• begin(): Returns an iterator to the first element in the set.
• end(): Returns an iterator to the theoretical element that follows the last element in the set.
• size(): Returns the number of elements in the set.
• max_size(): Returns the maximum number of elements that the set can hold.
• empty(): Returns whether the set is empty.

Inserting an Iterator Range into a Set

It takes the range and inserts the element one by one into the BST if it is not already present in it in O(N log(N)) time. 

Syntax:

set_name.insert(iterator Starting_position, iterator Ending_position);

Note: It insert element of Starting_position, Ending_position) which means Ending_position element is excluded.

Example:

C++

// C++ program to Insert
// Elements In set using
// Iterator Range from
// an Array
#include <iostream>
#include <set>
#include <vector>

using namespace std;

int main()
{

    set<int> s;

    int arr[] = { 1, 2, 4, 3, 5 };
    int N = sizeof(arr) / sizeof(arr[0]);

    s.clear();

    // Insert elements of array into set
    s.insert(arr, arr + N);

    cout << "Inserting an array of Size: " << N << endl;

    cout << "Size of set: " << s.size() << endl;

    // Print the element of set
    for (auto& i : s) {
        cout << i << " ";
    }

    return 0;
}

Output

Inserting an array of Size: 5
Size of set: 5
1 2 3 4 5 

Example 2:

C++

// C++ program to Insert
// Elements In set using
// Iterator Range from
// vector
#include <iostream>
#include <set>
#include <vector>

using namespace std;

int main()
{

    vector<int> v = { 1, 2, 4, 3, 5 };
    set<int> s;

    // Insert elements of vector into set
    s.insert(v.begin(), v.end());

    cout << "Inserting a vector of Size: " << v.size()
         << endl;

    cout << "Size of set: " << s.size() << endl;

    // Print the element of set
    for (auto& i : s) {
        cout << i << " ";
    }

    cout << endl;

    return 0;
}

Output

Inserting a vector of Size: 5
Size of set: 5
1 2 3 4 5