Set

In C++, a set is a container that stores unique elements in a specific order. It is often used when we want to store a collection of elements where duplicates are not allowed.

Creating a Set

To create a set in C++, we need to include the <set> header file. We can then declare a set using the syntax std::set<T>, where T represents the type of the elements.

Here's an example of creating a set of integers:

1#include <set>
2
3int main() {
4  // Creating a set
5  std::set<int> mySet;
6
7  // Inserting elements into the set
8  mySet.insert(10);
9  mySet.insert(20);
10  mySet.insert(30);
11
12  return 0;
13}

Checking if an Element Exists

To check if a specific element exists in a set, we can use the count() function. It returns the number of elements matching a specific value.

Here's an example of checking if the element 20 exists in the set:

1if (mySet.count(20) > 0) {
2  // Element 20 exists in the set
3}

Removing an Element

To remove an element from a set, we can use the erase() function. It removes the element with a specific value from the set.

Here's an example of removing the element 10 from the set:

1mySet.erase(10);

Traversing a Set

To traverse a set, we can use an iterator that points to the beginning of the set (begin()) and iterate until it reaches the end of the set (end()).

Here's an example of traversing a set and printing each element:

1for (auto it = mySet.begin(); it != mySet.end(); it++) {
2  std::cout << *it << std::endl;
3}

Understanding how to use the set data structure in C++ is essential for managing unique collections of elements efficiently. It's commonly used in scenarios where we need to store and retrieve data without duplicates.

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#include <iostream>

#include <set>

​

int main() {

  // Creating a set

  std::set<int> mySet;

​

  // Inserting elements into the set

  mySet.insert(10);

  mySet.insert(20);

  mySet.insert(30);

​

  // Checking if an element exists in the set

  if (mySet.count(20) > 0) {

    std::cout << "Element 20 exists in the set" << std::endl;

  }

​

  // Removing an element from the set

  mySet.erase(10);

​

  // Traversing the set

  for (auto it = mySet.begin(); it != mySet.end(); it++) {

    std::cout << *it << std::endl;

  }

​

  return 0;

}