Important changes to the code

The most important thing to note about the code in Listing 5 is the following:

• The function signature for the function named doubleIt specifies a return value of type int instead of type void as was the case in the previous sample programs.
• The code in the function named doubleIt contains a return statement that was not needed in the previous sample programs.

Otherwise, the program in Listing 5 is straightforward.

The output

The screen output produced by the program is

a = 2
a doubled = 4