unordered_set clear() function in C++ STL
The unordered_set::clear() function is a built-in function in C++ STL which is used to clear an unordered_set container. That is, this function removes all of the elements from an unordered_set and empties it. All of the iterators, pointers, and references to the container are invalidated. This reduces the size of the container to zero.
Syntax:
unordered_set_name.clear()
Parameter: This function does not accepts any parameter.
Return Value: This function does not returns any value.
Below programs illustrate the unordered_set::clear() function:
Program 1:
CPP
// C++ program to illustrate the// unordered_set::clear() function#include <iostream>#include <unordered_set>using namespace std;int main(){ unordered_set<int> sampleSet; // Inserting elements sampleSet.insert(5); sampleSet.insert(10); sampleSet.insert(15); sampleSet.insert(20); sampleSet.insert(25); // displaying all elements of sampleSet cout << "sampleSet contains: "; for (auto itr = sampleSet.begin(); itr != sampleSet.end(); itr++) { cout << *itr << " "; } // clear the set sampleSet.clear(); // size after clearing cout << "\nSize of set after clearing elements: " << sampleSet.size(); return 0;} |
Output
sampleSet contains: 25 20 15 5 10 Size of set after clearing elements: 0
Program 2:
CPP
// C++ program to illustrate the// unordered_set::clear() function#include <iostream>#include <unordered_set>using namespace std;int main(){ unordered_set<string> sampleSet; // Inserting elements sampleSet.insert("Welcome"); sampleSet.insert("To"); sampleSet.insert("GeeksforGeeks"); sampleSet.insert("Computer Science Portal"); sampleSet.insert("For Geeks"); // displaying all elements of sampleSet cout << "sampleSet contains: "; for (auto itr = sampleSet.begin(); itr != sampleSet.end(); itr++) { cout << *itr << " "; } // clear the set sampleSet.clear(); // size after clearing cout << "\nSize of set after clearing elements: " << sampleSet.size(); return 0;} |
Output
sampleSet contains: For Geeks GeeksforGeeks Computer Science Portal Welcome To Size of set after clearing elements: 0
