Flash MX 2004 Games : Art to ActionScript

Flash MX 2004 Games
1 n = 25;
2 i = 10;
3 total = 1;
4
5 trace("Sum = " + sumUpTo(i));
6 trace("n = " + n);
7 trace("total = " + total);
8
9 function sumUpTo(n:Number):Number{
10 var total:Number = 0;
11
12 while (n>0){
13 total += n;
14 n--;
15 }
16
17 return total;
18 }
Listing 11.5 ‘Examples/Chapter11/debug07.fla’
Again we create some variables in the old way of just assigning them values. The new function
‘sumUpTo’ is passed a parameter, in this case the contents of the variable i. The function declaration
shows that this is supposed to be a number. If instead we pass a string then we get an error message.
The function is expected to return a number. Within the function we declare a number type
variable called ‘total’, which is not the same variable as created in line 3. The function decrements
the variable passed in as the parameter n, but this has no effect on the variable i because it is a
copy. Any attempt to manipulate it has no effect on the original. The end of the function returns
the value of the local variable ‘total’. Having returned from the function the original variables
assigned in lines 1 to 3 have been unaffected; the trace statements in lines 5 to 7 show this to be
the case.
Variable scope
‘Examples\Chapter11\debug08.fla’ illustrates another extremely common problem.
In this simple project we have a dynamic text box tracking the variable ‘count’ and a movie clip
with the instance name ‘counter’. The ‘counter’ clip has the following clip events.
1 onClipEvent(load){
2 count = 0;
3 }
4
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