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Index › Programming Questions & Help › Syntax Questions › While Loop Question
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While Loop Question (Read 705 times)
Dalage
While Loop Question
May 2nd, 2010, 3:18pm  
I am attempting Exercise 6-1 in 'Learning Processing'.

Could someone please explain why the line in red "float cDia = width*2;"wouldn't work on it's own.

The program worked fine after I added the blue line "cDia = width*2;" in setup.



float cDia = width*2;
float spacing = 20;
float colourChange = 30;
float cFill = 200;

void setup(){
cDia = width*2;
size(200,200);
background(255);
}

void draw(){

 ellipseMode(CENTER);

 while(cDia >= 0){
   stroke(0);
   fill(cFill);
   ellipse(width/2,height/2,cDia,cDia);
   cDia = cDia - spacing;
   cFill = cFill - colourChange;
   println("colour: " + cFill);
   println("Circle: " + cDia);
 }  
}
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blindfish
Re: While Loop Question
Reply #1 - May 2nd, 2010, 3:42pm  
Simple - 'width' is defined when you call size() in setup, so you can't refer to it before setup()...  Technically the blue line shouldn't work either as it's also before size(), which is why size() should always be the first call in setup...
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Where is the what if the what is in why?
 
Dalage
Re: While Loop Question
Reply #2 - May 2nd, 2010, 5:00pm  
Thanks blindfish.
It seems so obvious now that you have explained it.
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