How does this loop get screwed up?

vegastech · February 2010

I have this for loop programmed into a button press:

LOCAL_VAR integer nChannel		
FOR (nChannel=0;nChannel<4;nChannel++)

but it seems that when I press the button, the variable starts at 0, and then jumps to 4. Shouldn't it only increment by 1 after each press?

a_riot42 · February 2010

vegastech wrote: »
I have this for loop programmed into a button press:
LOCAL_VAR integer nChannel		
FOR (nChannel=0;nChannel<4;nChannel++)
but it seems that when I press the button, the variable starts at 0, and then jumps to 4. Shouldn't it only increment by 1 after each press?

Your for loop isn't going to stop after one time through and wait for you to hit the button again. Its going to execute the loop until nChannel is not less than 4 every time you hit the button. What were you expecting to happen?
Paul

Jorde_V · February 2010

It continues for as long as nChannel is less than 4, hence it will not stop before it reaches 4. What is it that you want to do?

Spire_Jeff · February 2010

here is some code to accomplish this:

button_event[dvTp,nBtn]{
  push:{
     local_var integer nChannel;
     nChannel = (nChannel+1)%4; //nChannel will cycle 0,1,2,3,0,1,2,3,0... 
  }
}

I think this should work.

Jeff

vegastech · February 2010

I want it to increment by 1 after each pass, and then stop until I press another button, until I have pressed 3 buttons. I have a variable array that I am trying to fill 3 digits with. My goal here is to press 3 numerics, and have a numeric load the 1st, then 2nd, and finally the 3rd spot, to then send out a 3 digit channel.

Spire_Jeff · February 2010

Try this:

define_variable
volatile integer nChannel = 1;

button_event[dvTp,nBtn]{
  push:{
     nChannel++;
     //Store button number data accordingly. 
  }
  release:{
    if(nChannel >= 3){
      nChannel = 1;
      //send data to device.
    }
  }
}

Jeff

ericmedley · February 2010

vegastech wrote: »

I want it to increment by 1 after each pass, and then stop until I press another button, until I have pressed 3 buttons. I have a variable array that I am trying to fill 3 digits with. My goal here is to press 3 numerics, and have a numeric load the 1st, then 2nd, and finally the 3rd spot, to then send out a 3 digit channel.

Yeah, a FOR loop doesn't work that way in Netlinx. Once started it will run on its own without stopping. There's not really a 'Next' command as you might see in other programming languages.

yuri · February 2010

first time i used a FOR loop in Netlinx i expected to "see" it count in the debug window.
But instead i just saw 0 -> 255

vegastech · February 2010

What about the Break command? Wouldn't that typically stop the loop after the first run?

John Gonzales · February 2010

vegastech wrote: »

What about the Break command? Wouldn't that typically stop the loop after the first run?

It'll break the FOR loop when it's encountered but it won't restart it.

--John

jjames · February 2010

Spire_Jeff wrote: »

define_variable
volatile integer nChannel = 1;

button_event[dvTp,nBtn]{
  push:{
     nChannel++;
     //Store button number data accordingly. 
  }
  release:{
    if(nChannel >= 3){
      nChannel = 1;
      //send data to device.
    }
  }
}

This is where a button_var (a variable only specific to a button event; broader scope than a local or stack, but smaller than a global) would come very handy. Unfortunately, in a circumstance like this we "waste" / unnecessarily use a global variable.

Anyway - I'd vouch for code like this.

How does this loop get screwed up?

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