The multimap clear() function is an inbuilt function in C++ STL which is used to remove all elements from the multimap container (which are destroyed), leaving the container with a size of 0.
Syntax :
mymultimap_name.clear()
Parameters: This function does not take any arguments.
Return Value: This function does not returns anything. The return type of the function is void. It just empties the whole container.
Below program illustrate the multimap::clear() function in C++:
// CPP program to illustrate the
// multimap::clear() function
#include <cstring>
#include <iostream>
#include <map>
using namespace std;
int main()
{
// Creating multimap of string and int
multimap<string, int> mymultimap;
// Inserting 3 Items with their value
// using insert function
mymultimap.insert(pair<string, int>("Item1", 10));
mymultimap.insert(pair<string, int>("Item2", 20));
mymultimap.insert(pair<string, int>("Item3", 30));
cout << "Size of the multimap before using "
<< "clear function : ";
cout << mymultimap.size() << '\n';
// Removing all the elements
// present in the multimap
mymultimap.clear();
cout << "Size of the multimap after using"
<< " clear function : ";
cout << mymultimap.size() << '\n';
return 0;
}
Output
Size of the multimap before using clear function : 3 Size of the multimap after using clear function : 0
Time Complexity: O(N), where N is the total number of elements in multimap.
