Some of the merge operation classes are provided in C++ STL under the header file “algorithm”, which facilitates several merge operations in a easy manner.

Some of them are mentioned below.

**merge(beg1, end1, beg2, end2, beg3)**:- This function merges two sorted containers and stores in new container in sorted order (merge sort). It takes 5 arguments, first and last iterator of 1st container, first and last iterator of 2nd container and 1st iterator of resultant container.**includes(beg1, end1, beg2, end2)**:- This function is used to check whether one sorted container elements are including other sorted container elements or not. Returns true if 1st container includes 2nd container else returns false.// C++ code to demonstrate the working of // merge() and include() #include<iostream> #include<algorithm> // merge operations #include<vector> // for vector using namespace std; int main() { // Initializing 1st vector vector<int> v1 = {1, 3, 4, 5, 20, 30}; // Initializing 2nd vector vector<int> v2 = {1, 5, 6, 7, 25, 30}; // Declaring resultant vector // for mergeing vector<int> v3(12); // Using merge() to merge vectors v1 and v2 // and storing result in v3 merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); // Displaying resultant container cout << "The new container after merging is :\n"; for (int &x : v3) cout << x << " "; cout << endl; // Initializing new vector vector<int> v4 = {1, 3, 4, 5, 6, 20, 25, 30}; // Using include() to check if v4 contains v1 includes(v4.begin(), v4.end(), v1.begin(), v1.end())? cout << "v4 includes v1": cout << "v4 does'nt include v1"; return 0; }

Output

The new container after merging is : 1 1 3 4 5 5 6 7 20 25 30 30 v4 includes v1

**inplace_merge(beg1, beg2, end) :-**This function is used to sort two consecutively placed sorted ranges in a single container. It takes 3 arguments, iterator to beginning of 1st sorted range, iterator to beginning of 2nd sorted range, and iterator to last position.// C++ code to demonstrate the working of // inplace_merge() #include<iostream> #include<algorithm> // merge operations #include<vector> // for vector using namespace std; int main() { // Initializing 1st vector vector<int> v1 = {1, 3, 4, 5, 20, 30}; // Initializing 2nd vector vector<int> v2 = {1, 5, 6, 7, 25, 30}; // Declaring resultant vector // for inplace_merge() vector<int> v3(12); // using copy to copy both vectors into // one container auto it = copy(v1.begin(), v1.end(), v3.begin()); copy(v2.begin(), v2.end(), it); // Using inplace_merge() to sort the container inplace_merge(v3.begin(),it,v3.end()); // Displaying resultant container cout << "The new container after inplace_merging is :\n"; for (int &x : v3) cout << x << " "; cout << endl; return 0; }

Output:

The new container after inplace_merging is : 1 1 3 4 5 5 6 7 20 25 30 30

**set_union(beg1, end1, beg2, end2, beg3)**:- This function computes the set union of two containers and stores in new container .It returns the iterator to the last element of resultant container. It takes 5 arguments, first and last iterator of 1st container, first and last iterator of 2nd container and 1st iterator of resultant container . The containers should be sorted and it is necessary that new container is resized to suitable size.**set_intersection(beg1, end1, beg2, end2, beg3)**:- This function computes the set intersection of two containers and stores in new container .It returns the iterator to the last element of resultant container. It takes 5 arguments, first and last iterator of 1st container, first and last iterator of 2nd container and 1st iterator of resultant container . The containers should be sorted and it is necessary that new container is resized to suitable size.

One way to implement set-union and set-intersection in sorted ranges can be found here// C++ code to demonstrate the working of // set_union() and set_intersection() #include<iostream> #include<algorithm> // for merge operations #include<vector> // for vector using namespace std; int main() { // Initializing 1st vector vector<int> v1 = {1, 3, 4, 5, 20, 30}; // Initializing 2nd vector vector<int> v2 = {1, 5, 6, 7, 25, 30}; // Declaring resultant vector // for union vector<int> v3(10); // Declaring resultant vector // for intersection vector<int> v4(10); // using set_union() to compute union of 2 // containers v1 and v2 and store result in v3 auto it = set_union(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); // using set_intersection() to compute intersection // of 2 containers v1 and v2 and store result in v4 auto it1 = set_intersection(v1.begin(),v1.end(), v2.begin(), v2.end(), v4.begin()); // resizing new container v3.resize(it - v3.begin()); // resizing new container v4.resize(it1 - v4.begin()); // Displaying set union cout << "Union of two containers is : "; for (int &x : v3) cout << x << " "; cout << endl; // Displaying set intersection cout << "Intersection of two containers is : "; for (int &x : v4) cout << x << " "; cout << endl; return 0; }

Output:

Union of two containers is : 1 3 4 5 6 7 20 25 30 Intersection of two containers is : 1 5 30

**set_difference(beg1, end1, beg2, end2, beg3)**:- This function computes the set difference of two containers and stores in new container .It returns the iterator to the last element of resultant container. It takes 5 arguments, first and last iterator of 1st container, first and last iterator of 2nd container and 1st iterator of resultant container . The containers should be sorted and it is necessary that new container is resized to suitable size.- s
**et_symmetric_difference(beg1, end1, beg2, end2, beg3)**:- This function computes the set symmetric difference of two containers and stores in new container .It returns the iterator to the last element of resultant container. It takes 5 arguments, first and last iterator of 1st container, first and last iterator of 2nd container and 1st iterator of resultant container . The containers should be sorted and it is necessary that new container is resized to suitable size.// C++ code to demonstrate the working of // set_difference() and set_symmetric_difference() #include<iostream> #include<algorithm> // for merge operations #include<vector> // for vector using namespace std; int main() { // Initializing 1st vector vector<int> v1 = {1, 3, 4, 5, 20, 30}; // Initializing 2nd vector vector<int> v2 = {1, 5, 6, 7, 25, 30}; // Declaring resultant vector // for difference vector<int> v3(10); // Declaring resultant vector // for symmetric_difference vector<int> v4(10); // using set_difference() to compute difference // of 2 containers v1 and v2. auto it = set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); // using set_symmetric_difference() to compute // symmetric_difference/ of 2 containers auto it1 = set_symmetric_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), v4.begin()); // resizing new container v3.resize(it - v3.begin()); // resizing new container v4.resize(it1 - v4.begin()); // Displaying set difference cout << "Difference of two containers is : "; for (int &x : v3) cout << x << " "; cout << endl; // Displaying set symmetric_difference cout << "symmetric_difference of two containers is : "; for (int &x : v4) cout << x << " "; cout << endl; return 0; }

Output:

Difference of two containers is : 3 4 20 Symmetric difference of two containers is : 3 4 6 7 20 25

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