Author Topic: Question about Division  (Read 32 times)


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Question about Division
« on: February 10, 2017, 09:56:18 am »
I know that it was mentioned a while ago that division always returns a Float.

So I have been doing things like this:

Code: [Select]
Dim Value As Integer
..... stuff
Value = ((Value + List(currentsample)) / 2).ToInteger()

everywhere. Now I have to say this seems to be odd behavior, as most languages would simply do integer arithmetic in this case. If I were to do this:

Code: [Select]
Value = ((Value + List(currentsample)) / 2.0).ToInteger()

I would expect to have to cast to an integer, as 2.0 is explicitly a Float, and so Value etc. would usually be promoted to a Float.

This means that common constructs like:

Code: [Select]
Value /= 2

Don't work as Value is an Integer and the division returns a float (but Value *= 2, +=, -= etc do work - this seems inconsistent).

Looking at the documentation, it gives two division operators (never noticed that before!).

This is what the documentation says:

Shared Operator /(x As Integer, y As Integer) As Integer
Shared Operator \(x As Integer, y As Integer) As float

So according to the documentation, / should return an Integer, and \ should return a float. In fact, having tested this, it is the opposite way round.

So this does work:

Code: [Select]
Dim Value As Integer
..... stuff
Value = (Value + List(currentsample)) \ 2

And Value \= 2 works too!

I would really like to go through my code and remove all the unneeded type casting, but I'm not sure which is the right form. The documentation does not agree with the compiler.

So which is right? should I refactor my code, or will the compiler be fixed and I can just take out all the type casts as is (in the future)?


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Re: Question about Division
« Reply #1 on: February 14, 2017, 10:17:20 am »
The documentation is incorrect for integer but correct for short and byte.

The "\" operation divides two integer types (Byte, Short or Integer) and promotes one of the variables to the larger types if they are not the same, divides and returns a variable of that type. So two bytes return a type, a Short and a byte return a short, etc.

The "/" operation divides two variables by promoting the two variables to an float and return a float.