std::unordered_map::max_size

size_type max_size() const noexcept;

Returns the maximum number of elements the container is able to hold due to system or library implementation limitations, i.e. std::distance(begin(), end()) for the largest container.

Parameters

(none).

Return value

Maximum number of elements.

Complexity

Constant.

Notes

This value typically reflects the theoretical limit on the size of the container. At runtime, the size of the container may be limited to a value smaller than max_size() by the amount of RAM available.

Example

#include <iostream>
#include <unordered_map>
 
int main()
{
    std::unordered_map<char,char> s;
    std::cout << "Maximum size of a 'unordered_map' is " << s.max_size() << "\n";
}

Maximum size of a 'unordered_map' is 18446744073709551615

See also