I see... yes, the non-intuitive thing about arrays in .NET, that I tend to forget, is that you can't cast an Object[] to a Foo[], even if every single element in the Object[] happens to be an instance of Foo.
IOW, the following code throws InvalidCastException: object[] foos = new object[3]; foos[0] = new Foo(); foos[1] = new Foo(); foos[2] = new Foo(); Foo[] bar = (Foo[])foos; // throws! Thanks for the clarity, Joroen. -S On Fri, 10 Jan 2003 14:07:51 +0100, Jeroen Frijters <[EMAIL PROTECTED]> wrote: >As long as the cast succeeds performance should be the same, if the cast >fails, isinst is much faster than castclass (because castclass has to throw >an exception, which is expensive). > >Note that neither of these instructions look at the elements of the array, >i.e. only the type of the array is considered, not its contents. > >Regards, >Jeroen > >> -----Original Message----- >> From: Moderated discussion of advanced .NET topics. >> [mailto:[EMAIL PROTECTED]] On Behalf Of >> Shawn A. Van Ness >> Sent: Thursday, January 09, 2003 22:29 >> To: [EMAIL PROTECTED] >> Subject: [ADVANCED-DOTNET] Performance: castclass vs. isinst? >> >> >> Which is faster? For arrays, do both castclass and isinst >> have to walk the list of elements, checking each one? >> >> I find I never know when to write >> >> string[] foo = >> (string[])arraylist.ToArray(typeof(string)); // castclass >> vs >> string[] foo = >> arraylist.ToArray(typeof(string)) as string[]; // isinst >> >> The latter is easer to type (fewer parens ;-) but seems to >> give fits to VS's intellisense and auto-formatting features. :-( >> >> Cheers, >> -Shawn >> http://www.arithex.com/ >> >> You can read messages from the Advanced DOTNET archive, >> unsubscribe from Advanced DOTNET, or >> subscribe to other DevelopMentor lists at http://discuss.develop.com. >> > >You can read messages from the Advanced DOTNET archive, unsubscribe from Advanced >DOTNET, or >subscribe to other DevelopMentor lists at http://discuss.develop.com. You can read messages from the Advanced DOTNET archive, unsubscribe from Advanced DOTNET, or subscribe to other DevelopMentor lists at http://discuss.develop.com.
