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Showing content from https://www.tutorialspoint.com/cpp_standard_library/cpp_deque_get_allocator.htm below:

C++ Deque::get_allocator() Function

The C++ std::deque::get_allocator() function is used to return the copy of the allocator object associated with the deque. This allocator object is responsible for managing the memory allocations and deallocation for the elements within the deque. By accessing the allocator, we can control or customize the memory management.

Following is the syntax for std::deque::get_allocator() function.

allocator_type get_allocator() const noexcept;

It does not accept any parameter.

It returns an allocator associated with deque.

This function never throws exception.

The time complexity of this function is Constant i.e O(1)

In the following example, we are going to consider the basic usage of the get_allocator() function.

#include <iostream>
#include <deque>
#include <memory>
int main()
{
    std::deque<char> a;
    std::allocator<char> x = a.get_allocator();
    char* y = x.allocate(1);
    x.construct(y, 'A');
    std::cout << "Value constructed in allocated memory: " << *y << std::endl;
    x.destroy(y);
    x.deallocate(y, 1);
    return 0;
}

Output of the above code is as follows −

Value constructed in allocated memory: A

Consider the following example, where we are going to create a another deque using the same allocator as the first deque.

#include <iostream>
#include <deque>
int main()
{
    std::deque<int> a = {1, 22,333,4444};
    std::deque<int> b(a.get_allocator());
    b.push_back(123);
    b.push_back(345);
    for (int val : b) {
        std::cout << val << " ";
    }
    std::cout << std::endl;
    return 0;
}

Following is the output of the above code −

123 345 

deque.htm

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