implicitly declared variables in subs/functions

[bitvast]

It says in the manual:

Implicitly declared variables always have a global scope, meaning that they are visible to all functions and routines in the whole program. Variables which are used and declared within a SUB or FUNCTION also by default have a global scope.

So I would expect x to be 10 at the end of this program, but it isn't:


FUNCTION f()
  x = 0
  INCR x, 5
  RETURN x
END FUNCTION

'this statement has no effect
INCR x, 5

PRINT f()
PRINT x
5
5

[Pjot]

Hi bitvast,

So I would expect x to be 10 at the end of this program

No, it isn't. Because when you call the function f() after the INCR, the value of 'x' is reset back to 0 in the function f().

BR
Peter

[bitvast]

Thanks Peter, no bug then.

It seems that BaCon, unlike some languages, doesn't allow two variables to have the same name, even when one is LOCAL to a sub/function and the other GLOBAL. But I guess that's probably a good thing.

[Pjot]

Well, it works like this:

- If a variable explicitly is declared as a global variable (using DECLARE) then such a variable is visible in functions and subs too. This means, that a variable with such name cannot also exist with a local scope.
- Similar for implicit declared variables, which always have a global scope. In your demo program, the 'INCR x, 5' in the main section implicitly declares the variable 'x' globally.

However, if you explicitly declare a variable as LOCAL in each sub/function then this is not problem:

FUNCTION f()
LOCAL x
INCR x, 5
RETURN x
END FUNCTION

FUNCTION g()
LOCAL x
INCR x, 6
RETURN x
END FUNCTION

PRINT f()
PRINT g()

HTH
Peter

[bitvast]

Peter,

Thanks for clearing that up. I was writing a demo program for the tutorial, but kept getting errors.