// ============================================
// Week 6: Pointers (p. 4)

int* p1 = 0;
cout << sizeof(p1) << endl; // 8
double* p2 = 0;
cout << sizeof(p2) << endl; // 8






// ============================================
// Week 6: Pointers (p. 8)

int a = 10;
int* p1 = &a;
cout << "value of a = " << a << endl;
cout << "value of p1 = " << p1 << endl;
cout << "address of a = " << &a << endl;
cout << "address of p1 = " << &p1 << endl;
cout << "value of the variable pointed by p1 = " << *p1 << endl;







// ============================================
// Week 6: Pointers (p. 10)

// left
int a = 10;
int* ptr = NULL; 
ptr = &a;
cout << *ptr; // ?
*ptr = 5; 
cout << a;    // ?
a = 18; 
cout << *ptr; // ?

// right
int a = 10;
int* ptr1 = NULL; 
int* ptr2 = NULL;
ptr1 = ptr2 = &a;
cout << *ptr1; // ?
*ptr2 = 5;     
cout << *ptr1; // ?
(*ptr1)++; 
cout << a;     // ?






// ============================================
// Week 6: Pointers (p. 11)

int* p2 = NULL;
cout << "value of p2 = " << p2 << endl;
cout << "address of p2 = " << &p2 << endl;
cout << "value of the variable pointed by p2 = " << *p2 << endl;





// ============================================
// Week 6: Pointers (p. 18)

int c = 10;
int& d = c; // declare d as c¡¦s reference
d = 20;
cout << c << endl; // 20






// ============================================
// Week 6: Pointers (p. 19)

void swap (int& x, int& y);
int main()
{
  int a = 10, b = 20;
  cout << a << " " << b << endl; 
  swap(a, b);
  cout << a << " " << b << endl; 
}	
void swap (int& x, int& y)
{
  int temp = x;
  x = y;
  y = temp;
}





// ============================================
// Week 6: Pointers (p. 21)

void swap(int* ptrA, int* ptrB)
{
  int temp = *ptrA;
  *ptrA = *ptrB;
  *ptrB = temp;
}





// ============================================
// Week 6: Pointers (p. 22)

void swap(int* ptrA, int* ptrB)
{
  int* temp = ptrA;
  ptrA = ptrB;
  ptrB = temp;
}






// ============================================
// Week 6: Pointers (p. 26)

int a = 10;
int* ptr = &a;
cout << ptr++;  
  // just an address
  // we don't know what's here
cout << *ptr; 
  // dangerous! 





// ============================================
// Week 6: Pointers (p. 27)

double a[3] = {10.5, 11.5, 12.5};
double* b = &a[0];
cout << *b << " " << b << endl;  // 10.5
b = b + 2; 
cout << *b << " " << b << endl;  // 12.5
b--;
cout << *b << " " << b << endl;  // 11.5





// ============================================
// Week 6: Pointers (p. 28)

double a[3] = {10.5, 11.5, 12.5};
double* b = &a[0];
double* c = &a[2];
cout << c - b << endl; // 2, not 16!





// ============================================
// Week 6: Pointers (p. 29)

int x[3] = {1, 2, 3};
for(int i = 0; i < 3; i++)
  cout << *(x + i) << " "; // 1 2 3
for(int i = 0; i < 3; i++)
  cout << *(x++) << " "; // 1 2 3
for(int i = 0; i < 3; i++)
  cout << *(x + i) << " "; // unpredictable





// ============================================
// Week 6: Pointers (p. 30)

int x[3] = {1, 2, 3};
for(int i = 0; i < 3; i++)
  cout << x[i] << " "; // x[i] == *(x + i) 
for(int i = 0; i < 3; i++)
  cout << *(x++) << " "; // error!