C++ Unordered_map Library - get_allocator() Function

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Description

The C++ function std::unordered_map::get_allocator() returns an allocator associated with unordered_map.

Declaration

Following is the declaration for std::unordered_map::get_allocator() function form std::unordered_map header.

C++11

allocator_type get_allocator() const noexcept;

Parameters

None

Return value

Returns an allocator associated with unordered_map.

Exceptions

This member function never throws exception.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::unordered_map::get_allocator() function.

#include <iostream>
#include <unordered_map>

using namespace std;

int main(void) {
   unordered_map<char, int> um;
   pair<const char, int> *p;

   p = um.get_allocator().allocate(5);

   cout << "Allocated size = " <<  sizeof(*p) * 5 << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Allocated size = 40