# std::unordered_map<Key,T,Hash,KeyEqual,Allocator>::max_bucket_count

From cppreference.com
< cpp‎ | container‎ | unordered map

size_type max_bucket_count() const; |  | (since C++11)

Returns the maximum number of buckets the container is able to hold due to system or library implementation limitations.

### Parameters

(none)

### Return value

Maximum number of buckets.

### Complexity

Constant.

### Example

Run this code

    #include <iostream>
    #include <unordered_map>

    int main()
    {
        struct Ha { std::size_t operator()(long x) const { return std::hash<long>{}(x); }; };

        auto c1 = std::unordered_map<char, long>{};
        auto c2 = std::unordered_map<long, long>{};
        auto c3 = std::unordered_map<long, long, std::hash<int>>{};
        auto c4 = std::unordered_map<long, long, Ha>{};

        std::cout
            << "Max bucket count of\n" << std::hex << std::showbase
            << "c1: " << c1.max_bucket_count() << '\n'
            << "c2: " << c2.max_bucket_count() << '\n'
            << "c3: " << c3.max_bucket_count() << '\n'
            << "c4: " << c4.max_bucket_count() << '\n'
            ;
    }

Possible output:

    Max bucket count of
    c1: 0xfffffffffffffff
    c2: 0xfffffffffffffff
    c3: 0xfffffffffffffff
    c4: 0xaaaaaaaaaaaaaaa

### See also

bucket_count (C++11) | returns the number of buckets (public member function)

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