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C++ Map Library - clear() Function
Description
The C++ function std::multimap::clear() destroys the multimap by removing all elements and sets size of multimap to zero.
Declaration
Following is the declaration for std::multimap::clear() function form std::map header.
C++98
void clear();
C++11
void clear() noexcept;
Parameters
None
Return value
None
Exceptions
This member function never throws exception.
Time complexity
Linear i.e. O(n)
Example
The following example shows the usage of std::multimap::clear() function.
#include <iostream> #include <map> using namespace std; int main(void) { /* Multimap with duplicates */ multimap<char, int> m { {'a', 1}, {'a', 2}, {'b', 3}, {'c', 4}, {'c', 5}, }; cout << "Initial size of multimap = " << m.size() << endl; m.clear(); cout << "Size of multimap after clear operation = " << m.size() << endl; return 0; }
Let us compile and run the above program, this will produce the following result −
Initial size of multimap = 5 Size of multimap after clear operation = 0
map.htm
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