2D Collision problems - 2d

Question

I have the following code:
function collisionDetect(left1,right1,top1,bottom1,left2,right2,top2,bottom2,dir)
local left,right,top,bottom=false,false,false,false
if left1<right2 then left=true end
if right1>left2 then right=true end
if top1>bottom2 then top=true end
if bottom1<top2 then bottom=true end
if dir.x>0 and (top or bottom) then
if right then return 1 end
elseif dir.x<0 and (top or bottom) then
if left then return 2 end
elseif dir.y>0 and (left or right) then
if bottom then return 3 end
elseif dir.y<0 and (left or right) then
if top then return 4 end
end
return 0
end
left1, right1, etc. are arguments containing the position of the respective bounding box (box 1 or 2).
dir is a "Vector2" (contains an x and y property).
For some reason, my code is returning collisions for objects no where near by. Any ideas?
EDIT:
I have solved my problem, here is the code for anybody googling the subject.
(It's in Lua, a pretty straight forward and simple to interpret language)
function collisionDetect(left1,right1,top1,bottom1,left2,right2,top2,bottom2,dir)
local insideHorizontal=false
local insideVertical=false
if left1<right2 then insideHorizontal=true end
if right1>left2 then insideHorizontal=true end
if top1>bottom2 then insideVertical=true end
if bottom1<top2 then insideVertical=true end
if insideHorizontal and insideVertical then
return true
end
return false
end

Answer 1

Have a look at this for a nice collision detection tutorial/algorithm.
Essentially:
bool check_collision( SDL_Rect A, SDL_Rect B )
{
//...
//Work out sides
//...
//If any of the sides from A are outside of B
if( bottomA <= topB )
{
return false;
}
if( topA >= bottomB )
{
return false;
}
if( rightA <= leftB )
{
return false;
}
if( leftA >= rightB )
{
return false;
}
//If none of the sides from A are outside B
return true;
}
Or, in terms of your code:
function collisionDetect(left1,right1,top1,bottom1,left2,right2,top2,bottom2,dir)
if bottom1<=top2 then return true end
if top1>=bottom2 then return true end
if right1<=left2 then return true end
if left1<=right2 then return true end
return false
end
(this isn't a language I know, so I'm guessing a bit)