std::string 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 <string>
#include <climits>

int main()
{
    std::string s;
    std::cout
        << "Maximum size of a string is " << s.max_size() << " ("
        << std::hex << std::showbase << s.max_size()
        << "), pointer size: " << std::dec
        << CHAR_BIT*sizeof(void*) << " bits\n";
}

Possible output

Maximum size of a string is 9223372036854775807 (0x7fffffffffffffff), pointer size: 64 bits