Re: Unsure about Something

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From: Richard A. Lowe (chadich_at_yumspamyumYahoo.com)
Date: 02/16/04 

Date: Sun, 15 Feb 2004 22:33:10 -0600

Well, form a purely IL (intermediate language) perspective the variable 'n'
IS being created with a *method-wide* scope level.

The simple example:
 for (int i = 0; i < 10; ++i) {
 int n = i;
 }

produces the following relevant IL:
.method private hidebysig static void Main(string[] args) cil managed
{
  .entrypoint
  .maxstack 2
  .locals init ([0] int32 i,
           [1] int32 n)

The ".locals init" line defines two int32's at the start of the method.
Indeed, I don't think there is any other way to do this (declare a local
variable) in IL - so enforcing scope more granular than method level is a
job for the compiler.

Richard 

-- 
C#, .NET and Complex Adaptive Systems:
http://blogs.geekdojo.net/Richard
"C# Learner" <csharp@learner.here> wrote in message
news:fmf0301n6pslqsnr4gf19uo2gbbp3dt61d@4ax.com...
> "Bjorn Abelli" <bjorn_abelli@DoNotSpam.hotmail.com> wrote:
>
> <snip>
>
> >> Okay, but does _a_ get re-created each time the "for (int j..." loop
> >> is entered, or is it created only once, when SomeMethod() is entered?
> >
> >In each iteration you have declared a new variable with the name "a".
This
> >variable is "destroyed" for each turn, so in that sense you can say that
> >it's "re-created" (though it's not the same variable, but a "new"
variable
> >for each iteration).
>
> Hi,
>
> I've previously tried Googling on this subject and have found that
> some say the above is true and some say the opposite is true.
>
> i.e.:
>
> for (int i = 0; i < 10; ++i) {
> int n = i;
> }
>
> Some say that _n_ is only *created* once, whereas others say that it
> is re-created on each iteration of the loop.
>
> So in the former case, the integer variable _n_ would be created once.
> In the latter, 10 integer variables would eventually be created; one
> for each iteration of the loop.
>
> I'm still not sure which side to believe...
>
> I'd like to use the whole declaration inside the loop, for
> readability, instead of declaring the int outside the loop once then
> using it in the loop.  However, if this is going to cost in terms of
> performance I wouldn't want to do it.
>
> >// Bjorn A

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