Hi Bill,
check in http://root.cern.ch/root/Cint.phtml?limitations
the item about scope.
Cheers, Fons.
William Hanlon wrote:
>
> Hi,
>
> I do not have a copy of the ANSI C++ rules in front of me, but I
> believe that there are some discrepancies between ROOT and standard
> C++ variable scope rules.
>
> For example, I expect a variable declared in the body of an if
> statement to be defined throughout the body of that statement like:
>
> if (int foo = bar(arg))
> {
> cout << "foo is " << foo << endl;
> }
> else
> {
> cout << " foo is 0 " << endl;
> }
>
> This does not work in ROOT. The error returned is:
>
> Warning: Automatic variable Int_tfoo allocated in global scope FILE:test.C LINE:12
>
> but works exactly as expected when compiled using a c++
> compiler
>
> Additionally variables declared in a for loop exist outside of the
> loop. Try running the following in ROOT and compile a version using
> your favorite compiler and you will see a big difference between the
> two outputs:
>
> int i = 66;
>
> for (int i = 0; i < 10; i++)
> {
> int k;
>
> k++;
>
> cout << "in loop k: " << k << endl;
>
> }
>
> cout << "outside loop i: " << i << endl;
> cout << "outside loop k: " << k << endl;
>
> In fact this should not even compile using a compiler since k is not
> declared outside of the loop. Additionally this program run through
> ROOT will say that i is 10, but it should be 66 shouldn't it?
>
> I have also run into problems with variables not being removed between
> functions calls to the same function in loops.
>
> Are these variable scoping differences intended, being worked on, or
> am I just wrong about this? I haven't seen anyone else remark about
> this in the roottalk digest.
>
> Thanks for any comments,
> Bill
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