On Wed, 17 Mar 2004, kractor wrote:
> Michael Van Canneyt wrote: > > >On Tue, 16 Mar 2004, kractor wrote: > > > > > > > >>spent a few moments going over the docs in the manual re: exception > >>handling. for some reason it just doesn't seem to be sinking in, as > >>nothing i've tried as of yet has managed to stop prog from crashing when > >>data in input that's of a different type than program is expecting > >>(string as opposed to integer, for example). > >> > >>as i said, i'm pretty sure that its something really small and obvious, > >>i'll include a few lines here ... maybe someone can spot my mistake ... > >>pretty sure its the EConvertError and that there's a pre-defined error > >>type that I just haven't come across yet. > >> > >> try > >> readln(NewAlbum.Year); > >> except > >> on EConvertError do NewAlbum.Year := 0; > >> end; > >> > >> > > > >This should be: > > > > > > try > > readln(NewAlbum.Year); > > except > > on E : EConvertError do NewAlbum.Year := 0; > > end; > > > >Michael. > > > >_______________________________________________ > >fpc-pascal maillist - [EMAIL PROTECTED] > >http://lists.freepascal.org/mailman/listinfo/fpc-pascal > > > > > > > tried your suggestion and when i attempted to input string when prog > expecting integer value, it gave following error > > An unhandled exception occurred at 0x004012CC : > EInOutError : Invalid input > > so, i tried changing the EConvertError to EInOutError, little code paste > follows > > try > readln(NewAlbum.Year); > except > on E : EInOutError do NewAlbum.Year := 0; > end; > write('label: '); > readln(NewAlbum.alLabel); > write('tracks: '); > readln(NewAlbum.NumTracks); > > what's happening now is that when "invalid" data type is entered which > triggers the exception handle, the program is "skipping" the > readln(NewAlbum.alLabel) command and resuming apparently normal > operations on the very next line [write('tracks: ');]. when valid data > is entered, the program naturally doesn't trigger the exception handle > and everything works normally. I have been able to reproduce this. However, I'm not sure what the cause it. My guess is that the end-of-line is not consumed before the exception is raised, and therefore the readln(NewAlbum.alLabel); line gets an empty input line. Delphi does consume the end-of-line, and waits for the input of the label. This is a very tricky issue, I think the core FPC list needs to discuss it. For the moment, I would do like this; Var A : String; begin readln(A); NewAlbum.Year:=StrToIntDef(A,0); write('label: '); readln(NewAlbum.alLabel); write('tracks: '); readln(NewAlbum.NumTracks); This avoids the exception. Michael. _______________________________________________ fpc-pascal maillist - [EMAIL PROTECTED] http://lists.freepascal.org/mailman/listinfo/fpc-pascal
