std::map<Key,T,Compare,Allocator>::max_size

 

C++

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Feature test macros (C++20)

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Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

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forward_list (C++11)

list

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set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

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span (C++20)

 

std::map

Member functions

map::map

map::~map

map::operator=

map::get_allocator

Element access

map::at

map::operator[]

Iterators

map::beginmap::cbegin (C++11)

map::endmap::cend (C++11)

map::rbeginmap::crbegin (C++11)

map::rendmap::crend (C++11)

Capacity

map::empty

map::size

map::max_size

Modifiers

map::clear

map::insert

map::insert_or_assign (C++17)

map::emplace (C++11)

map::emplace_hint (C++11)

map::try_emplace (C++17)

map::erase

map::swap

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map::merge (C++17)

Lookup

map::count

map::find

map::contains (C++20)

map::equal_range

map::lower_bound

map::upper_bound

Observers

map::key_comp

map::value_comp

Non-member functions

std::swap

erase_if (C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides (C++17)

 

size_type max_size() const;		(until C++11)
size_type max_size() const noexcept;		(since C++11)

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 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

Run this code

#include <iostream>
#include <map>
 
const char* separate(unsigned long long n)
{
    static char buf[64];
 
    int i{sizeof(buf) - 1}, j{};
    buf[i] = '\0';
 
    do {
        buf[--i] = '0' + (n % 10);
        if (j++ % 3 == 2)
            buf[--i] = '\'';
    } while (n /= 10);
 
    return buf + i + (buf[i] == '\'' ? 1 : 0);
}
 
int main()
{
    std::map<char,char> s;
    std::cout << "Maximum size of a 'map' is " << separate(s.max_size()) << "\n";
}

Possible output:

Maximum size of a 'map' is 576'460'752'303'423'487

See also

size	returns the number of elements (public member function)