Function not returning a value

BlitzPlus Forums/BlitzPlus Beginners Area/Function not returning a value

Normsthename

(Posted 2008) [#1]

According to the Help, a function can return a value.
I am trying to get the following test code to work, but to no avail.
Basically I want the function to return true or false if the objects have collided.
The Remmed out Imagescollide line works if it is unremmed....

Graphics 800,600,0,2 
SetBuffer BackBuffer()

Global player = CreateImage(50,50)
Global box = CreateImage(800,600) 

Cls
;Draw Box
Rect 50,50,600,400,0
GrabImage box,0,0

Cls
;Draw player
Oval 0,0,20,20,1
GrabImage player,0,0


;Main Loop
Repeat
Cls

DrawImage box,0,0
DrawImage player,MouseX(),MouseY()

If collision=1 Then Text 280,240,"COLLISION!!!"
;If ImagesCollide(player,MouseX(),MouseY(),0,box,0,0,0) Then Text 280,240,"COLLISION!!!"

Flip 
Until KeyDown(1)
End


Function collision()
If ImagesCollide(player,MouseX(),MouseY(),0,box,0,0,0) Then
Return True
Else
Return False 
End If 
End Function

Any ideas would be much appreciated!

Thanks

Andy

GfK	(Posted 2008) [#2]

Spot the difference...

If collision=1 Then Text 280,240,"COLLISION!!!"

If collision() Then Text 280,240,"COLLISION!!!"

You can also express this as If Collision() = True. Try getting into the habit of using True and False instead of 1 and 0. Makes your code much more readable.

Normsthename

(Posted 2008) [#3]

Thanks GfK!
I have been trying for a day or so to sort this.......

You can also express this as If Collision() = True. Try getting into the habit of using True and False instead of 1 and 0. Makes your code much more readable.

Well it is the beginners area!......

I have always have had a nasty habit of writing spaghetti code.. I must try harder!

Thanks again

Andy

GfK	(Posted 2008) [#4]

Well it is the beginners area!......

Yep, but no harm in mentioning it. :D

I wish I'd had somebody to explain to me about code consistency when I first started programming 22 years ago.

Zethrax

(Posted 2008) [#5]

As GFK indicated, function names need to be followed by parenthesis if you want the function to return a value. The parenthesis are optional if you don't need to return a value.

Eg.

Function MyFunc1()
; Function code.
Return x
End Function

Function MyFunc2( a )
; Function code.
Return x
End Function

If MyFunc1() Then whatever
If MyFunc2( b ) Then whatever

This also applies to native Blitz functions.

Note that some Blitz commands that return a value are actually language constructs, rather than functions, and putting parenthesis after them will cause an error. Some examples are: New, Before, After, First, Last.

Normsthename

(Posted 2008) [#6]

Cheers Bill!

Thanks for your input

Andy