#include <iostream>

/*
	Most of the code here violates the C++ standard.
	It is designed to show you some of the things that can happen
	when you do the wrong things with stack based memory
*/

/* Declare some output functions */
void output_values(int*,int,double,int*,int,double);
void output_array(int*);


int main() {
	/*
	 Create two arrays and two integer variables, on the stack since they
	 are local variables of the main function
	*/
	int array_one[10] = {1,2,3,4,5,6,7,8,9,10};
	int variable_one = 1;
	double double_one = 1.1;
	int array_two[10] = {2,4,6,8,10,12,14,16,18,20};
	int variable_two = 2;
	double double_two=2.2;

	/* Output the variables...  */
	output_values(array_one,variable_one,double_one,array_two,variable_two,
		double_two);

	/*
	 Get pointers to the arrays and variables
	*/
	int *array_one_pointer = array_one;
	int *variable_one_pointer = &variable_one;
	int *array_two_pointer = array_two;
	int *variable_two_pointer = &variable_two;

	/*
	 Output the addresses of the arrays and variables
	*/
	std::cout<<"Array One Address    : "<<array_one_pointer<<std::endl;
	std::cout<<"Variable One Address : "<<variable_one_pointer<<std::endl;
	std::cout<< "Array Two Address   : " << array_two_pointer<<std::endl;
	std::cout<<"Variable Two Address : "<<variable_two_pointer<<std::endl;

	/*
	 On the department Sun machines the stack grows down and thus the 
	 varaibles declared first are at higher addresses - on other
	 machines/compilers it may be different. So assumming that work
	 out how far apart the variables are
	*/
	std::cout <<"Array Two is "<< (array_two_pointer-variable_two_pointer)
	          <<" int sized spaces higher than Variable Two.\n";
	std::cout <<"Variable One is "<<(variable_one_pointer-array_two_pointer)
	          <<" int sized spaces higher than Array Two.\n";
	std::cout <<"Array One is "<< (array_one_pointer-variable_one_pointer)
	          <<" int sized spaces higher than Variable One.\n";
	/*
	 Keep a copy of how far variable one is from variable two
	*/
	int variable_two_to_variable_one = variable_one_pointer
						 - variable_two_pointer;
	
	/*
	 Modify variable one through the variable two pointer
	*/
	std::cout << "Execute the following code : variable_two_pointer["
	          <<variable_two_to_variable_one<<"] = 42\n";
	variable_two_pointer[variable_two_to_variable_one] = 42;

	/* Output the variables...  */
	output_values(array_one,variable_one,double_one,array_two,variable_two,
		double_two);

	/*
	 Modify everything except variable two using array two
	*/
	int size = (array_one_pointer-array_two_pointer)+10;
	std::cout << "Modify "<<size<<" elements of array_two\n";
	for(int i=0;i<size;i++)
		array_two[i] = i*10;
	/* Output the variables...  */
	output_values(array_one,variable_one,double_one,array_two,variable_two,
		double_two);

	std::cout << "Notice that running off the ends of arrays doesn't"
		  << " always crash the program\n"
	          << "However, unrelated variables that change is bad\n";
}

void output_values(int *array1, int var1, double d1, int* array2, int var2, double d2)
{
	std::cout << "Array One is    : ";
	output_array(array1);
	std::cout << std::endl;
	std::cout << "Variable One is : " << var1<<std::endl;
	std::cout << "Double One is   : " << d1<<std::endl;
	std::cout << "Array Two is    : ";
	output_array(array2);
	std::cout << std::endl;
	std::cout << "Variable Two is : " << var2<<std::endl;
	std::cout << "Double Two is   : " << d2<<std::endl;

}

void output_array(int *array)
{
	std::cout << '{' << array[0];
	for (int i=1;i<10;i++)
		std::cout << ", " << array[i];
	std::cout << '}';
}