[Gambas-user] WHILE and AND: please explain me....

[Fabián Flores Vadell]

2010/5/4, Leonardo Miliani <leonardo at ...1237...>:
> I'm working with this little piece of code, it's the Insertion Sort:
>
> PUBLIC SUB InsertionSort(matrix AS String[])
> DIM i, j AS Integer
> DIM x AS String
>
>   FOR i = 1 TO (matrix.Count - 1)
>     x = matrix[i]
>     j = i - 1
>     WHILE j >= 0 AND matrix[j] > x
>       matrix[j + 1] = matrix[j]
>       j -= 1
>     WEND
>     matrix[j + 1] = x
>   NEXT
> END
>
> But I get an "Out of bound" error in the WHILE test, because j begins
> -1.
>
> Usually (in other languages this is the behavior) the AND test checks
> the first condition, and if it is false then it checks the second one.
> OK... but shouldn't Gambas bypass the WHILE statement because j is
> negative?
>
> --
> Leonardo Miliani
> www.leonardomiliani.com

Hi Leonardo. You have to avoid than j can become negative when you use
it like index on the "matrix" array. So, I think that you can do it,
modifying the matrix index in the logical test, using the IF()
function:

WHILE j >= 0 AND matrix[IF(j>0, j, 0)] > x


-- 
Fabián Flores Vadell
www.speedbooksargentina.blogspot.com