std::vector::max_size

From cppreference.com
< cpp‎ | container‎ | vector

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

Possible output:

Maximum size of a 'vector' is 18446744073709551615

See also

returns the number of elements
(public member function)
returns the number of elements that can be held in currently allocated storage
(public member function)