error message help

[sammi7]

What is it you are trying to achieve?
<im trying to make the game Snake and add in bonus food to make the snake grow more


What is the problem you are having?
<whenever i try and eat the bonus food(blue) it says variable has no value and i dont know how to fix it.>


Describe what you have tried to solve this problem
<Answer Here>


Post any relevant code (You may choose to attach the file instead of posting the code if it is too long)
<Answer Here>

Turing:

View.Set ("graphics,offscreenonly") var segX : array 1 .. 1000 of int % x-position of segments var segY : array 1 .. 1000 of int % y-position of segments var foodX : int  % x-position of the food foodX := Rand.Int (30, 300) var foodY : int % y-position of the food foodY := Rand.Int (100, 300) %BONUS FOOD var bonusFoodX : int bonusFoodX := Rand.Int (30, 300) var bonusFoodY : int bonusFoodY := Rand.Int (30, 300) var numSegs : int % number of segments on the snake % 1 - up, 2 - right, 3 - down, 4 - left var direction : int direction := 2 var keys : array char of boolean Input.KeyDown (keys) numSegs := 3 % starting number of segments % STARTING POSITION OF THE 3 SEGMENTS segX (1) := 200 segY (1) := 100 segX (2) := 180 segY (2) := 100 segX (3) := 180 segY (3) := 80 loop     Input.KeyDown (keys) % update keyboard info     % DRAWING THE BODY     for i : 2 .. numSegs         Draw.FillOval (segX (i), segY (i), 10, 10, black)     end for     %DRAWING THE HEAD     Draw.FillOval (segX (1), segY (1), 10, 10, 13)     % DRAWING THE FOOD     Draw.FillOval (foodX, foodY, 12, 12, brightred)     Draw.FillOval (bonusFoodX, bonusFoodY, 12, 12, blue)     % user input     if keys (KEY_UP_ARROW) = true then % moving the snake up         direction := 1     elsif keys (KEY_RIGHT_ARROW) = true then % moving the snake right         direction := 2     elsif keys (KEY_DOWN_ARROW) = true then % movng the snake down         direction := 3     elsif keys (KEY_LEFT_ARROW) = true then % moving the snake left         direction := 4     end if     % To do : CHECK IF IT HIT THE WALLS     if segX (1) >= maxx then         segX (1) := -7     elsif segX (1) <= -7 then         segX (1) := maxx - 7     end if     if segY (1) >= maxy then         segY (1) := -7     elsif segY (1) <= -7 then         segY (1) := maxy - 7     end if     % check if food is eaten and move the food     if whatdotcolour (segX (1), segY (1)) = brightred then % TODO: actually check real food         numSegs := numSegs + 1 % adding a segment when food is eaten         foodX := Rand.Int (30, 400) % moving the food         foodY := Rand.Int (60, 300) % moving the food     end if     %check if hit bonus food     if whatdotcolour (segX (1), segY (1)) = blue then         numSegs := numSegs + 3         bonusFoodX := Rand.Int (30, 400) % moving the food         bonusFoodY := Rand.Int (60, 300) % moving the food     end if         % MOVEMENT     % Move Body     for decreasing i : numSegs .. 2         segX (i) := segX (i - 1)         segY (i) := segY (i - 1)     end for     % Move Head     if direction = 1 then     % up         segY (1) := segY (1) + 20     elsif direction = 2 then     % right         segX (1) := segX (1) + 20     elsif direction = 3 then     % down         segY (1) := segY (1) - 20     elsif direction = 4 then     % left         segX (1) := segX (1) - 20     end if     % TODO: check if hit self     if whatdotcolour (segX (1), segY (1)) = black then         numSegs := 3         delay (200)     end if     View.Update ()     delay (100)     cls () end loop

Please specify what version of Turing you are using
<4.1>

[Tony]

sammi7 @ Thu Dec 08, 2011 6:07 pm wrote:

it says variable has no value and i dont know how to fix it.

You should assign a value to that variable.

A more helpful question -- what do you think the value of the variable is, when it's accessed? Well, it turns out that it didn't have any value assigned before use. E.g.

code:

var value : int put 5 + value

What should the answer be? Obviously that doesn't make sense until variable actually holds some value. Trace back through your program to see what's going on.

[sammi7]

but i already declared it at the top. and when i tried taking out the part about the whatdotclour for the bonus food it worked....Why does it only happen when i add the bonus food check in?

[Tony]

sure, I also declared the variable called "value" at the top of my example. What's the output?

[sammi7]

ya i know but it works with the original red food....thats what i dont understand.....How do i make it work with both foods?

[Tony]

well, you are doing something to grow the snake with regular food (assigning values to variables) that you are not doing to bonus food (variable doesn't get assigned a value before it is used).

Though looking at your implementation, it could be that regular food works just by a coincidence.