Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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while is a reserved keyword in Processing, like the keywords if and else, which you’ve
already looked at. A while loop will execute the code between its open and closed curly
braces as long as the condition between the parentheses is true. In the example, the condition
will always be true. true is actually another reserved keyword in Processing and Java
that always means, well . . . true. Can you see why I didn’t want you to run this loop example?
It will never stop running, as there is no exit condition (i.e., a condition that when
reached will cause the code to continue past the loop). Nasty loops like this are called
infinite loops, and they are to be avoided. Of course, you can force the Processing application
to quit, so don’t panic if you did try running it (against my sage advice). Here’s an
improved and safe version of that last demonic loop:
int x = 0;
while (x=0) {
println (x);
x -= 100;
}
This loop outputs the values 1000 through 0, decrementing by 100 each cycle, or iteration,
of the loop. Also, I set the condition using >=, so 0 was output as well.
do . . . while
A while loop will only execute if the condition is true. However, there are times when
you’ll want a loop to execute at least once no matter what. The do...while loop is sort of
a backward while loop that always executes at least once, regardless of whether the condition
is true. After the first iteration of the loop, though, it behaves just like a regular
while loop. Here are two examples:
//example 1.
int x = 50;
do {
println(x);
x += 1;
}
while(x