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C++ Unordered_map::get_allocator() Function
The C++ std::unordered_map::get_allocator() function is used to obtain a copy of an allocator associated with the unordered_map. The allocator is responsible for allocating and deallocating memory for the element stored in the unordered map.
This function does not modify the unordered_map and does not throw any exceptions.
Syntax
Following is the syntax of std::unordered_map::get_allocator() function.
allocator_type get_allocator() const;
Parameters
This function does not accepts any parameter
Return value
This function returns an allocator object.
Example 1
In this following example, we are demonstrating the usage of the 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; }
Output
Let us compile and run the above program, this will produce the following result −
Allocated size = 40
Example 2
Consider the following example, we declare an unordered map object and use the get_allocator() function to allocate pairs to the unordered map. If a pair is allocated, it returns true; otherwise, it returns false.
#include <iostream> #include <unordered_map> #include <string> using namespace std; int main() { unordered_map<int, int> uMap; unordered_map<int, int>::allocator_type umap = uMap.get_allocator(); cout << "Is allocator Pair<int, int> : "<< boolalpha <<(umap == allocator<pair<int, int> >()); return 0; }
Output
If we run the above code it will generate the following output −
Is allocator Pair<int, int> : true