unordered_map max_size in C++ STL (original) (raw)

Last Updated : 18 Sep, 2024

The

**unordered_map::max_size

is a built in function in C++ STL. It returns maximum number of elements which unordered_map can hold. Maximum number of elements in any container depends upon system and library implementation.

Syntax

size unordered_map.max_size()

Parameters:

It does not accept any parameters.

Return type:

Unsigned integer a container can hold maximum elements.

Example 1

CPP `

// C++ program to illustrate the // unordered_map::max_size function #include <bits/stdc++.h> using namespace std;

int main() {

// declaration of unordered_map
unordered_map<int, int> sample;

cout << " Current size is :  " << sample.size() << endl;
cout << " max size is : " << sample.max_size() << endl;

// insert elements
sample.insert({ 1, 10 });
sample.insert({ 2, 10 });
sample.insert({ 3, 10 });
sample.insert({ 4, 10 });

cout << " Current size is :  " << sample.size() << endl;
cout << " max size is : " << sample.max_size() << endl;

return 0;

}

`

Output

Current size is : 0 max size is : 1152921504606846975 Current size is : 4 max size is : 1152921504606846975

Example 2

CPP `

// C++ program to illustrate the // unordered_map::max_size function #include <bits/stdc++.h> using namespace std;

int main() {

// declaration of unordered_map
unordered_map<char, int> sample;

cout << " Current size is :  " << sample.size() << endl;
cout << " max size is : " << sample.max_size() << endl;

// insert elements
sample.insert({ 'a', 10 });
sample.insert({ 'b', 10 });
sample.insert({ 'c', 10 });

cout << " Current size is :  " << sample.size() << endl;
cout << " max size is : " << sample.max_size() << endl;

return 0;

}

`

Output

Current size is : 0 max size is : 1152921504606846975 Current size is : 3 max size is : 1152921504606846975

Complexity :

Its complexity is constant.