map max_size() in C++ STL

The map::max_size() is a built-in function in C++ STL which returns the maximum number of elements a map container can hold. 

Syntax:

map_name.max_size()

Parameters: This function does not accept any parameters. 

Return Value: This function returns the maximum number of elements a map container can hold. 

CPP

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

int main()
{

    // initialize container
    map<int, int> mp1, mp2;
    mp1.insert({ 1, 2 });

    // max size of Non-empty map
    cout << "The max size of mp1 is " << mp1.max_size();

    // max size of Empty-map
    cout << "\nThe max size of mp2 is " << mp2.max_size();
    return 0;
}

Output:

The max size of mp1 is 461168601842738790
The max size of mp2 is 461168601842738790

Time Complexity –  Constant O(1)