unordered_multimap get_allocator in C++ STL

unordered_multimap::get_allocator() is a built in function in C++ STL which is used to get allocator of container unordered_mulitmap. Syntax:

Allocator_type get_allocator()

Parameters: This function does not accept any parameter. Return value: Returns an allocator associated with unordered_multimap. Below programs illustrate the working of unordered_multimap::get_allocator() function. Example-1: 

CPP

// CPP program to illustrate
// unordered_multimap get_allocator()
#include <bits/stdc++.h>
using namespace std;

int main()
{

    //'ump' is object of 'unordered_multimap'
    unordered_multimap<int, int> ump;

    //'allocator_type' is inherit in 'unordered_multimap'
    //'u' is object of 'allocator_type'
    unordered_multimap<int, int>::allocator_type u = ump.get_allocator();

    // Comparing the Allocator with Pair<int, int>
    cout << "Is allocator Pair<int, int> : "
         << boolalpha
         << (u == allocator<pair<int, int> >());

    return 0;
}

Output:

Is allocator Pair : true

Example-2: 

CPP

// CPP program to illustrate
// unordered_multimap get_allocator()
#include <bits/stdc++.h>
using namespace std;

int main(void)
{
    unordered_multimap<char, int> um;
    pair<const char, int>* a;

    a = um.get_allocator().allocate(8);

    cout << "Allocated size = " << sizeof(*a) * 8 << endl;

    return 0;
}

Output:

Allocated size = 64

Time complexity: O(1).

Auxiliary space: O(1).