Game Development Reference
Using increment and decrement operators
There's a slightly more efficient way to write this code. Updating values incrementally, as you did before,
is such a common and useful thing that AS3.0 has specialized operators that do the work for you.
Operators are symbols such as =, -, + and *, which perform specialized tricks with
values, such as assigning, adding, or subtracting them.
The two new operators that you'll use are called the increment and decrement operators. Update
the kjQl>qppkj?he_g and kj@ksj>qppkj?he_g event handlers so that they use these operators:
1. Modify the kjQl>qppkj?he_g and kj@ksj>qppkj?he_g event handlers so that they reflect the
changes shown following. (I haven't included the pn]_a directives, and you can remove them if
you want to, but leaving them in is just fine, too! It won't affect how the program runs.)
2. Save the I]ej*]o file and test the project.
The functionality of the program is exactly the same, but I simplified the code a bit by using the decre-
and the increment operator:
All these operators do is assign the new value back into the property on the left of the operator sign.
The -= operator subtracts the value, and the += operator adds it.
Incrementing and decrementing are a game designer's staple, so get used to using them because you'll
be seeing them a lot from now on.