Collision Detection Help

[Harrison.Kevin]

I have read through threads on collision detection, but I'm still having issues getting myself to understand how it works.

Here is the code to the current project I have:

Turing:

var chars : array char of boolean var x1 : int := 1 var x2 : int := x1 + 10 var y1 : int := 1 var y2 : int := y1 + 10 var xv : real := 0 var yv : real := 0 var g : real := 1 var ground : boolean := true setscreen ("graphics:450;450,offscreenonly,nobuttonbar,title:Testing Screen") loop     Input.KeyDown (chars)     if chars ('w') and y2 < maxy and ground = true then         yv += 8     end if     if chars ('a') and x1 > 0 then         xv -= 1     elsif chars ('d') and x2 < maxx then         xv += 1     elsif chars (KEY_ESC) then         exit     end if     if y1 > 0 then         yv -= g     elsif y1 < 0 then         yv := 0         y1 := 0     end if     if xv > 0 then         xv -= 0.5     elsif xv < 0 then         xv += 0.5     end if     if x1 < 0 then         x1 := 0         xv := 0     elsif x2 > maxx then         x1 := maxx - 10         xv := 0     end if     if y2 > maxy then         y1 := maxy - 10         yv := 0     end if     if y1 = 0 then         ground := true     else         ground := false     end if     x1 += round(xv)     y1 += round(yv)     x2 := x1 + 10     y2 := y1 + 10     Draw.FillBox (x1, y1, x2, y2, black)     Draw.FillBox (0, 0, 450, 450, cyan)     Draw.FillBox (70, 0, 120, 80, black)     Draw.FillBox (200, 0, 250, 100, black)     Draw.FillBox (320, 0, 450, 100, blue)     var font : int     font := Font.New("serif:18")     Draw.Text ("FINISH", 350, 35, font, white)     Font.Free(font)     Draw.FillBox (x1 - 1, y1 - 1, x2 + 1, y2 + 1, white)     locate(1, 1)     View.Update     delay (10)     cls end loop

I am trying to make it so when the last box declared touches the other 2 black boxes, the last box declared will be set back to 0.

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Mod Edit: Change quote tag to use syntax="turing" tags.

[Insectoid]

What parts don't you understand?