array of type bad code !
BlitzMax Forums/BlitzMax Beginners Area/array of type bad code !
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| Could you help me to understand what's bad with this code ? Thanks ! My goal is to replace list by arrays into my game to access quickly and directly to an occurence (avoid a lot of 'for-eachin MyList-next loops) ! Strict Global Rect_list : TList = CreateList() Type TRect Field Id : Int Field x : Int Field y : Int Field r : Int Field g : Int Field b : Int Function Create:TRect (id, x,y) Local r:TRect = New TRect r.Id = Id r.x = x r.y = y r.r = Rand (0,255) r.g = Rand (0,255) r.b = Rand (0,255) ListAddLast Rect_list, r End Function Function Draw_all_with_list () For Local r:TRect = EachIn Rect_list SetColor r.r,r.g,r.b DrawRect r.x, r.y, 32,32 Next SetColor 255,255,255 End Function Method Draw_it () SetColor r,g,b DrawRect x, y, 32,32 SetColor 255,255,255 End Method End Type Graphics 800,600 Global array_of_rect : TRect[] Local NbRect = Rand (100,200) For Local i=1 To NbRect TRect.Create (i,Rand (0,800),Rand (0,600)) Next array_of_rect = New TRect[NbRect] For Local i=0 To NbRect - 1 array_of_rect[i] = TRect.Create (i,Rand (0,800),Rand (0,600)) Next While Not KeyDown (KEY_ESCAPE) Cls TRect.Draw_all_with_list() array_of_rect[15].Draw_it() ' <---- i want display item 15 : ERROR : attempt to access field or null object Flip Wend |
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oups, corrected myself Function Create:TRect (id, x,y) Local r:TRect = New TRect r.Id = Id r.x = x r.y = y r.r = Rand (0,255) r.g = Rand (0,255) r.b = Rand (0,255) ListAddLast Rect_list, r Return r ' <---- i've forgot this ! End Function |
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| There is no reason this code should not work. works here without any problem, so you most likely have some other problem. (you are on BM 1.22, right?) |
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| Thanks Dreamora, i've corrected myself the code by adding the 'return r' line ;-) |
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| Ah so that meant that this actually solved the problem. thought you meant it more of a "correction to above code" posting where you forgot to copy / write something. but none the less: good it works now |
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but i don't understand why the following code doesn't work.Strict Global array_of_rect : TRect[] Type TRect Field Id : Int Field x : Int Field y : Int Field r : Int Field g : Int Field b : Int Function Create:TRect (id, x,y) Local r:TRect = New TRect r.Id = Id r.x = x r.y = y r.r = Rand (0,255) r.g = Rand (0,255) r.b = Rand (0,255) Return r End Function Function Draw_all () For Local r:TRect = EachIn array_of_rect SetColor r.r,r.g,r.b DrawRect r.x, r.y, 32,32 Next SetColor 255,255,255 End Function Method Draw_it () SetColor r,g,b DrawRect x, y, 32,32 SetColor 255,255,255 End Method End Type Graphics 800,600 For Local i=0 To 99 array_of_rect = New TRect[i+1] array_of_rect[I] = TRect.Create (i,Rand (0,800),Rand (0,600)) Next 'array_of_rect.sort While Not KeyDown (KEY_ESCAPE) Cls TRect.Draw_all() array_of_rect[15].Draw_it() Flip Wend |
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| Thats quite easy: With array_of_rect = new TRect[i+1] you replace the old one, ie all the objects within as well. What you would need to do there is slicing: array_of_rect = array_of_rect[..i+1] BUT: if you raise it by one, this would be the worst idea you could have as it is massively slowing down. If you use slicing, only do it by length*2 and length/2 (as general rule) |
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| You have your slice wrong and you're creating 2 new trect each loop. |
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