The C++ Programming Language

using namespace std;

struct X {
 int i;

 // This does not utomatically convert an int to X. I was WRONG here.
 X(int pi) : i(pi) {
  std::cout << "i is " << pi << "\n";
 }

 X operator+(int j) // Adding int to class aka x+1 types... Must return another x or x&
 {
   cout << "j is " << j <<"\n";
   return X(i+j);
 }
};

struct Y {
 int i;

 // This does not automatically convert an X to Y. I was WRONG here.
 Y(X x)
 {
   std::cout << "In y(x) ctor\n";
  i = x.i;
 }

 Y operator+(X pX)  // Adding x to class aka y+x types. Must return another y or y&
 {
   std::cout << "In y::operator+(x) with val " << pX.i << "\n";
   return Y( X(i + pX.i) );
 }

 // Convert y to int
 operator int() // Converrts y to int. Will return int even if the func sig doesn't say so..
 {
   return i;
 }

};

extern X operator*(X pX, Y pY)
{
  std::cout << "x is " << pX.i << " and y is " << pY.i << "\n";
  return X(pX.i * pY.i);
}

extern int f(X pX)
{
  std::cout << "In f(X)\n";
  return pX.i;
}

/*
extern int f(int x)
{
  std::cout << "In f(int)\n";
  return x;
}
*/

X x = 1;

Y y = x;

int i = 2;



int main()

{

std::cout << "Before\n";    
std::cout << "**" << i + 10; // Simple Integer Add
std::cout << "After\n";  

std::cout << "Before\n";    
x = x + 10; // Simple Integer Add
std::cout << "**" << x.i << "\n";
std::cout << "After\n";  

std::cout << "Before\n";    
//x = 10 + x; // Simple Integer Add not permitted..
std::cout << "**" << x.i << "\n";
std::cout << "After\n";  

/*
std::cout << "Before\n";    
y = y + 10;
std::cout << "**" << y.i << "\n";
std::cout << "After\n";  
*/

/*
std::cout << "** Before\n";    
//y = 
10 + y;
std::cout << "**" << 10 + y << "\n";
std::cout << "After\n";  
*/

//y + X(10); // y operator+(X)

//y + X(10) * y; // extern op followed by y operator+(X) ;

/*

  std::cout << "Before\n";  
x + y + i; // INVALID or x operator+(int) after y reduces to an int followed Anothr x operator+(int)
std::cout << "After\n";  
std::cout << 106 + y; // x+y -> y + y -> y + x .. Actually it outputs an int :P
std::cout << "After\n";  
*/

std::cout << "B4 x is " << x.i << " and i is " <x * x + i; // extern X operator*(X, Y) ; followed by x operator+(int) ;
std::cout << "After\n";  

std::cout << "Since there is ctor conv between int and x. The following is valid\n";  
f(7) ; // extern int f(X) ;


std::cout << "Since there is no conv from y to x, the following is invalid\n";  
//f(y) ; // INVALID or f(y) to f(int) to f(X)


std::cout << "####### Before $$$$$$$$\n";
y + y; // y operator+(X)
std::cout << y + y << "\n";
std::cout << "GHJHHJJHJHn After *((**(()( \n";


return 0;
}