The C++ function std::unordered_multimap::count() returns the number of mapped values associated with key k.
Following is the declaration for std::unordered_multimap::count() function form std::unordered_map() header.
size_type count(const key_type& k) const;
k − Key for search operation.
Returns number of values associated with key.
Linear i.e. O(n)
The following example shows the usage of std::unordered_multimap::count() function.
#include <iostream> #include <unordered_map> using namespace std; int main(void) { unordered_multimap<char, int> umm = { {'a', 1}, {'a', 2}, {'b', 3}, {'b', 4}, {'c', 5} }; cout << "Count of a = " << umm.count('a') << endl; cout << "Count of b = " << umm.count('b') << endl; cout << "Count of c = " << umm.count('c') << endl; return 0; }
Let us compile and run the above program, this will produce the following result −
Count of a = 2 Count of b = 2 Count of c = 1