C++ multimap - count() Function
The C++ multimap::count function returns the number of occurrences of a specified key in the multimap container.
Syntax
size_type count (const key_type& k) const;
size_type count (const key_type& k) const;
Parameters
k |
Specify key to search for. |
Return Value
Number of elements with specified key in the multimap container.
Time Complexity
Logarithmic i.e, Θ(log(n)).
Example:
In the example below, the multimap::count function is used to find out the number of occurrences of specified key in the multimap called MyMMap.
#include <iostream>
#include <map>
using namespace std;
int main (){
multimap<string, string> MyMMap;
multimap<string, string>::iterator it;
MyMMap.insert(pair<string, string>("USA", "New York"));
MyMMap.insert(pair<string, string>("USA", "Washington"));
MyMMap.insert(pair<string, string>("CAN", "Toronto"));
MyMMap.insert(pair<string, string>("CAN", "Montreal"));
MyMMap.insert(pair<string, string>("IND", "Delhi"));
string MyStr[3] = {"CAN", "IND", "USA"};
for(int i = 0; i < 3; i++) {
string j = MyStr[i];
cout<<"\nThere are "<<MyMMap.count(j)<<" elements with key "<<j<<": ";
for(it = MyMMap.equal_range(j).first; it!=MyMMap.equal_range(j).second; it++)
cout<<it->second<<" ";
}
return 0;
}
The output of the above code will be:
There are 2 elements with key CAN: Toronto Montreal There are 1 elements with key IND: Delhi There are 2 elements with key USA: New York Washington
❮ C++ <map> Library
