Processing 1.0 - Processing Discourse - Beginner: Checking if a variable is declared

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Index › Programming Questions & Help › Syntax Questions › Beginner: Checking if a variable is declared

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Beginner: Checking if a variable is declared (Read 495 times)

haptic

Beginner: Checking if a variable is declared
Mar 11^th, 2007, 9:29pm

Hi,
I'm trying to move from ActionScript to processing and am trying to figure out a simple little problem.

I have 2 arrays, one that has values that update each frame (vals) and one that holds onto the last set of those values (lastVals). But on the first run through how can I make it so that the lastVals sees that vals has not been created yet and set itself to 0?

or possibly another way of approaching this... how can I make variables declared in setup() usable in draw()?

thanks

JohnG

Re: Beginner: Checking if a variable is declared
Reply #1 - Mar 11^th, 2007, 9:37pm

Code:

 int[] vals;
int[] lastVals;

void setup()
{
  //if you initialise vals here, lastvals will update at the start of draw just fine.
  //IF for some reason you don't want to set them up just yet, then
  //  the test below will check to see if vals has been filled.
}

void draw()
{
  if(vals!=null)
  {
    arraycopy(vals,lastVals);
  }
  //set up this frames vals next.
  vals=new int[10]; //actually it's better to do this in setup
			  // than creating a new array each frame.
}

haptic YaBB Newbies Offline Posts: 14	Re: Beginner: Checking if a variable is declared Reply #2 - Mar 11^th, 2007, 10:17pm thank you! that solved my problem.

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