STATIC Variable Initialisation

[Thunor]

Your help example :-

Code (glbasic) Select Expand

// STATIC / LOCAL
FOR i=0 TO 5
   foo()
NEXT
SHOWSCREEN
MOUSEWAIT

FUNCTION foo:
LOCAL  l = 5
STATIC s = 5
   INC l, 1
   INC s, 1
   PRINT "l="+l+" s="+s, 0, s*20
ENDFUNCTION...always prints "i=6 s=6" and that is all! This means that s is being reinitialised every time the function is executed which is wrong. It must be initialised the first time it is executed only.

Interestingly if I don't initialise s i.e. STATIC s it prints :-

i=6 s=1
i=6 s=2
i=6 s=3
i=6 s=4
i=6 s=5
i=6 s=6

... but it should be printing :-

i=6 s=6
i=6 s=7
i=6 s=8
i=6 s=9
i=6 s=10
i=6 s=11

Regards

[D2O]

Code (glbasic) Select Expand

// STATIC / LOCAL
FOR i=0 TO 5
   foo()
NEXT
SHOWSCREEN
MOUSEWAIT

FUNCTION foo:
LOCAL  l = 5
STATIC s
STATIC s_CTRL
IF s_CTRL = 0
s = 5
s_CTRL = 1
ENDIF  


   INC l, 1
   INC s, 1
   PRINT "l="+l+" s="+s, 0, s*20
ENDFUNCTION

[Thunor]

Thanks, an effective solution but I won't want the additional overhead of doing that for every static variable throughout my project. It would be easier to use global variables which defeats the point.

I've had a look in the cpp code generated by GLBasic for my project and I can see why my static variable is being reinitialised every time the function is called.

This GLBasic line :-

Code (glbasic) Select Expand

STATIC drag_id = UNDEFINED...is being translated to cpp as :-

Code (glbasic) Select Expand

static REGISTER_VAR_DEF(DGInt, drag_id,  UNDEFINED);
drag_id = UNDEFINED;UNDEFINED is a global variable and equals -1. The second line drag_id = UNDEFINED; is the problem. In fact any initialised variable will look similar to the above even though REGISTER_VAR_DEF is being passed an initial value.

[Kitty Hello]

Oh no! Huge bug!

[Thunor]

Oh no! Huge bug!

Hehe, sorry

I've decided to use D²O's method above for the time being, or something similar. One CTRL flag could be used to initialise many static variables so it's not such an overhead as I originally thought.

[AndyH]

Hey, I've found another odd thing with STATIC.  Try this code:

Code (glbasic) Select Expand

LOCAL i
FOR i=0 TO 10
LOCAL tt = test()
PRINT tt,0,i*8
NEXT

SHOWSCREEN
MOUSEWAIT


FUNCTION test:
STATIC _xx
INC _XX,1
RETURN _XX
ENDFUNCTIONIt should print out numbers in steps of 1, but it steps in twos.  OUTPUT = 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22

The offending line is:

Code (glbasic) Select Expand

LOCAL tt = test()Change this to

Code (glbasic) Select Expand

LOCAL tt
tt = test()And it all works.  Output is now (as expected) = 1,2,3,4,5,6,7,8,9,10,11

Is this related or a separate bug?

[Thunor]

The real issue is not static or local but variable initialisation.

GLBasic converts glbas to cpp like so :-

Code (glbasic) Select Expand

LOCAL tt = test()

...results in...

REGISTER_VAR_DEF(DGInt, tt,  test());
tt = test();...so I think you can see why it's incrementing in 2s. By the time you print tt, test() has been executed twice.

The reason it works if you seperate LOCAL tt is this :-

Code (glbasic) Select Expand

LOCAL tt
tt = test()

...results in...

REGISTER_VAR_DEF(DGInt, tt, 0);
tt = test();The same thing happens with static variable initialisation although the consequences are different.

You can simply refrain from using LOCAL in this way to prevent this problem from occuring.

BTW look in C:\Documents and Settings\user\Local Settings\Temp\glbasic\ to view your converted source code.

[Kitty Hello]

oughta be fixed in new update.