Set Basics
Basic Set Operations in C++
BeginnerTopic: STL Containers Programs
C++ Set Basics Program
This program helps you to learn the fundamental structure and syntax of C++ programming.
#include <iostream>
#include <set>
using namespace std;
int main() {
// Create set
set<int> numbers;
// Insert elements
numbers.insert(5);
numbers.insert(2);
numbers.insert(8);
numbers.insert(1);
numbers.insert(5); // Duplicate, will be ignored
numbers.insert(3);
// Display set
cout << "Set elements (sorted and unique): ";
for (int num : numbers) {
cout << num << " ";
}
cout << endl;
// Check if element exists
if (numbers.find(5) != numbers.end()) {
cout << "Element 5 found in set" << endl;
}
// Count occurrences (0 or 1 for set)
cout << "Count of 5: " << numbers.count(5) << endl;
cout << "Count of 10: " << numbers.count(10) << endl;
// Size
cout << "Set size: " << numbers.size() << endl;
// Erase element
numbers.erase(5);
cout << "\nAfter erasing 5: ";
for (int num : numbers) {
cout << num << " ";
}
cout << endl;
// Lower and upper bound
set<int> s = {1, 2, 3, 5, 7, 9};
auto it_low = s.lower_bound(4); // First element >= 4
auto it_up = s.upper_bound(6); // First element > 6
cout << "\nLower bound of 4: " << *it_low << endl;
cout << "Upper bound of 6: " << *it_up << endl;
return 0;
}Output
Set elements (sorted and unique): 1 2 3 5 8 Element 5 found in set Count of 5: 1 Count of 10: 0 Set size: 5 After erasing 5: 1 2 3 8 Lower bound of 4: 5 Upper bound of 6: 7
Understanding Set Basics
Set is a container that stores unique elements in sorted order. Duplicates are automatically removed. Operations: insert(), find(), erase(), count(), lower_bound(), upper_bound(). Sets are implemented as balanced binary search trees, providing O(log n) operations. Useful for maintaining sorted, unique collections.
Note: To write and run C++ programs, you need to set up the local environment on your computer. Refer to the complete article Setting up C++ Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your C++ programs.