map count() function in C++ STL

The map::count() is a built-in function in C++ STL which returns 1 if the element with key K is present in the map container. It returns 0 if the element with key K is not present in the container.

Syntax:

map_name.count(key k)

Parameters: The function accepts a mandatory parameter k which specifies the key to be searched in the map container.

Return Value: The function returns the number of times the key K is present in the map container. It returns 1 if the key is present in the container as the map only contains a unique key. It returns 0 if the key is not present in the map container.

Below program illustrates the above function:

// C++ program to illustrate
// the map::count() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // initialize container
    map<int, int> mp;

    // insert elements in random order
    mp.insert({ 2, 30 });
    mp.insert({ 1, 40 });
    mp.insert({ 3, 60 });
    mp.insert({ 4, 20 });
    mp.insert({ 5, 50 });

    // checks if key 1 is present or not
    if (mp.count(1))
        cout << "The key 1 is present\n";
    else
        cout << "The key 1 is not present\n";

    // checks if key 100 is present or not
    if (mp.count(100))
        cout << "The key 100 is present\n";
    else
        cout << "The key 100 is not present\n";

    return 0;
}

Output:

The key 1 is present
The key 100 is not present