Java

INDEPENDENT TOPIC 02 – VARARGS
(thank you to Nick Petryna and Justin Michaud for their contributions)

LESSON NOTE

FUNCTION OVERLOADING

When learning programming, a common function to write is one that will calculate the average of a set of numbers. We could write a function that will calculate the average of three numbers. We could also do one for four numbers. And another for five numbers. And so on. Of course, this could get long!

If we really wanted to make a function that would work for any amount of numbers, the ideal solution would be to take an array in as argument. This way, the array can contain any amount of numbers.

The downside to requiring an array is that programmers that want to use the function now have to do the extra work of creating the array – which is often seen as an annoyance.

SOLUTION

We can now do this in a method prototype:

public double average(double… arr)

In this situation, arr will be an array of type int. The … means that the array arr will be automatically created based on the numbers of int arguments in the function call.

For example, here are different functions calls that could be made to the prototype above:

double ans1 = average(82, 91, 74, 85);

double ans2 = average(3, 5, 6, 6, 8, 2, 9, 12, 3, 5, 8, 2);

double ans3 = average(50, 60, 40);

EXAMPLE PROGRAM

The example below has a vararg function. That function is called three different times from the main function with different amounts of parameters.

RESULT

The code above will generate the following output:

SOURCE CODE

Click here for the above code in a text file.