Flash MX 2004 Games : Art to ActionScript

8 In
tip-top condition
Should I go to Barcelona at Easter? If I have the money, there are flights available and I can
get a hotel, then I’ll go. Life is full of decisions: should I take that job? Should I join a gym?
Should I make a cup of tea? Whenever you make a decision, you will consider a number of
options and in the end you will either decide to do something or you will choose not to. As
you embark on your programming career you may be thinking, if this doesn’t get any easier then
I’ll stick to producing artwork. In this chapter we look at making decisions in your programs
using the marvellous ‘if ’ statement. An ‘if ’ statement takes a logical argument that resolves to
true or false; none of the difficult in-between concepts for a computer, it’s either true or it’s false
and no half measures. Sometimes we need to combine several decisions before we come to our
final conclusion. Multiple decisions are handled using Boolean logic, which is introduced in this
chapter. We will illustrate some of these concepts using a keyboard-controlled walking bucket and
some very attractive lights. So without further ado let us set sail on the sea of conditions.
The marvellous ‘if ’ statement
Because it is almost impossible to write any program without making a decision, you have already
seen the ‘if ’ statement in action. The introductory chapter used the ‘if ’ statement and so too did
the last chapter. You probably had a good idea what was going on, but you were not properly
introduced. The marvellous ‘if ’ statement can be used in one of three different ways. The simplest
way is like this:
if (condition){
//Do something if condition is true
}
The line starts using ‘if ’, and then in brackets we put a condition. This can be anything that
evaluates to true or false. You can even put the keyword true in there and then the ‘if ’ statement
always evaluates to true, so the code in the curly brackets is always executed. Later in this chapter
we will look at the different conditions you can use.
The second variant of the ‘if ’ statement takes this form:
if (condition){
//Do something if condition is true
}else{
//Do something if condition is false
}
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