std::vector max_size() method

since C++20

// Const version only
constexpr bool max_size() const noexcept;

since C++11

// Const version only
bool max_size() const noexcept;

until C++11

// Const version only
bool 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 the container can hold.

Complexity

Constant - O(1).

Notes

This value typically reflects the theoretical limit on the size of the container, at most std::numeric_limits<difference_type>::max(). At runtime, the size of the container may be limited to a value smaller than max_size() by the amount of RAM available.

Example

Main.cpp

#include <iostream>
#include <locale>
#include <array>
 
int main()
{
    std::vector<char> q;
    std::cout.imbue(std::locale("en_US.UTF-8"));    
    std::cout << "Maximum size of the std::array is " << q.max_size() << '\n';
}

Possible output

Maximum size of a std::vector is 9,223,372,036,854,775,807