Pointer and reference example (C++)

pointer_reference_example.cpp

void add_one_to_int(int& number)
{
  // This increases the value of the parameter.
  // The value will persist outside of the function, because the reference is passed,
  // so the memory address is used.
  number++;
}

void add_one_to_int_using_pointer(int* number_pointer)
{
  // This function also increases the value of the parameter by accessing the
  // memory location.
  *number_pointer++;
}

int main()
{
  int num = 0;
  int* num_pointer;
  *num_pointer = 0;

  for (int i = 0; i < 5; i++)
  {
    add_one_to_int(num);
    add_one_to_int_using_pointer(num_pointer);
  }
  printf("num, num_pointer = %d, %d", num, *num_pointer);
  return 1;
}



// === INCORRECT EXAMPLES:

void add_one_to_int_THE_WRONG_WAY(int number)
{
  // This will not increase the value outside of the function, since the function
  // creates a copy of the input parameter.
  number++;
}

void add_one_to_int_using_pointer_THE_WRONG_WAY(int* number_pointer)
{
  // This function increases not the value at the address, but the memory address itself.
  // It also uses a copy of the memory address (a copy of the pointer variable), 
  // so nothing makes sense about this.
  number_pointer++;
}