std::map::max_size

size_type max_size() const;

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.

Exceptions

(none)	(until C++11)
`noexcept` specification: `noexcept`	(since C++11)

Complexity

Constant.

Notes

This value is typically equal to std::numeric_limits<size_type>::max(), and 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 <map>
 
int main()
{
    std::map<char,char> s;
    std::cout << "Maximum size of a 'map' is " << s.max_size() << "\n";
}

Possible output:

Maximum size of a 'map' is 18446744073709551615