I forgot about Boxing with respect to adding value types to a weakly-typed collection.
Regardless, it still seems like (at least with local variables) value-on- stack reference-in-heap still applies, considering a boxed value type is a reference. There is some mention that member variables may not follow this rule, which isn't surprising--especially for statics--but I haven't confirmed that yet. http://www.peterRitchie.com/ On Fri, 13 Jan 2006 08:28:52 +0100, Fabian Schmied <[EMAIL PROTECTED]> wrote: >> Also, I was under the impression that C# simply mapped array definitions >> to the Array class. So: >> >> S[] array = new S[10000]; >> >> is directly allocating a reference type. I was also under the impression >> that the Array type managed its own memory (e.g. in the above example it >> isn't allocating 10000 individual value types) > >This is true, S[] is a reference type, but the separate instances of S >are allocated on the heap in a contiguous block of memory (this is >just from my memory now, I'd have to look it up to be certain on how >it works). > >> I assume the value types in this example are allocated from the stack: >> ArrayList al = new ArrayList(); >> for(int i = 0; i < 10000; i++) >> { >> al.Add(i); >> } > >Well, yes and no. Of course, i is a local variable and its int value >lives on the stack. But when i is reassigned, the old value is simply >overwritten, so there is always just one integer object in the stack. >When the value of i is added to the ArrayList, it is boxed, i.e. >copied to the heap. So, there really are 10000 boxed int objects plus >one contiguous block of object references on the heap after this loop, >which is neither memory nor runtime efficient. > >With List<int>, however, I'd guess there would be a backing int[], so >it should be very efficient again. =================================== This list is hosted by DevelopMentor® http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
