C++ : Type punning examples

main.cpp

#include <iostream>

struct Entity
{
	int x;
	int y;

	int* get_position()
	{
		return &x;
	}
};

int main()
{
	
	Entity entity = { 10, 25 };

	std::cout << entity.get_position()[0] << "\n";  //10
	std::cout << entity.get_position()[1] << "\n";  //25

	int* pos = (int*)&entity;
	std::cout << pos <<"\n"; //adress
	std::cout << *(pos) << "\n"; // 10
	std::cout << *(pos + 1) << "\n"; // 25
	std::cout << pos[0] << "\n"; // 10
	std::cout << pos[1] << "\n"; // 25

	int y = *(int*)((char*)&entity + 4);
	std::cout << y << "\n"; // 25

	//if you wish just to access the value
	{
		int& value = *(int*)&entity;
		std::cout << "value : " << value << "\n";
	}
	
	
	{
		int& value = *((int*)&entity + 1);
		std::cout << "value : " << value << "\n";
	}
	
	{
		int& value = *((int*)&entity + 1);
		value += 100;
	}


	{
		int& value = *((int*)&entity + 1);
		std::cout << "value : " << value << "\n"; //125
	}

	{
		std::cout << "entity.y : " << entity.y << "\n"; //125
	}
}