Due at the end of lab.

For this lab you will be experimenting with functions that use 'pass-by-value' and 'pass-by-reference' for their arguments. There are four questions as part of the lab, and you will need to turn in your (short) answers to these questions.

• So far we have been using pass-by-value arguments, in which a value is passed to a function as an argument. Consider the following code:
  
  int x = 7;
  int y = 20;
  flip(x, y); // this is a function call
  cout << x << " " << y << endl; // should print 20 7
  
  Question 1) Could you write the code for the definition of the flip() function so that the values of x and y are switched? (so that x becomes 20 and y becomes 7.) Why or why not?


• Try compiling and running this test program code. Look carefully at the output and the code.
  
  Question 2) What do you notice about how the value of x changes after function1() is called?
  Question 3) What do you notice about how the value of x changes after function2() is called?
  Question 4) What is the difference in code between function1() and function2() besides the name of the functions?


• The & makes a function use 'pass-by-reference' instead of 'pass-by-value'. Pass-by-reference means that a reference to the variable - literally the variable's location (address) in memory - is passed to the function. Because the function knows the location of the variable in memory, when it makes a change to the variable that change affects the original variable's value as well.


• Using your new knowledge of pass-by-reference arguments, create the flip() function described in the first part of the lab using pass-by-reference. Your flip() function must take two arguments and switch the values associated with the two arguments. Write a main() function to demonstrate that the flip() function works.