Re: Question about a programme

On Feb 18, 3:38=A0pm, Janis <janis_papanag...@[EMAIL PROTECTED]
> wrote:
> On 18 Feb., 15:14, Ed Morton <mor...@[EMAIL PROTECTED]
> wrote:
>
>
>
>
>
> > On 2/18/2008 6:57 AM, Spiros Bousbouras wrote:
>
> > > On page 194 of "Effective AWK programming" we see the
> > > following programme:
>
> > > # rewind.awk --- rewind the current file and start over
> > > function rewind( =A0 =A0i)
> > > {
> > > =A0 =A0 # ****ft remaining arguments up
> > > =A0 =A0 for (i =3D ARGC; i > ARGIND; i--)
> > > =A0 =A0 =A0 =A0 ARGV[i] =3D ARGV[i-1]
> > > =A0 =A0 # make sure gawk knows to keep going
> > > =A0 =A0 ARGC++
> > > =A0 =A0 # make current file next to get done
> > > =A0 =A0 ARGV[ARGIND+1] =3D FILENAME
> > > =A0 =A0 # do it
> > > =A0 =A0 nextfile
> > > }
>
> > > Isn't the statement ARGV[ARGIND+1] =3D FILENAME
> > > superfluous ? In the loop when i gets the
> > > value ARGIND + 1 then the assignment
> > > ARGV[ARGIND + 1] =3D ARGV[ARGIND] will be executed
> > > and ARGV[ARGIND] always has the same value as
> > > FILENAME
>
> > But what if the current file is the last one? Then i =3D ARGC =3D
ARGIND=
 at the
> > start of the loop, so the loop's never entered so THEN that final
assign=
ment is
> > required. Although that works in this context since the functiona name
i=
mplies
> > it MUST be called while parsing a file, use of FILENAME meanse you
can't=
 execute
> > this type of general "****ft the arguments" function in a BEGIN section
s=
o I'm
> > not a big fan.
>
> While filename is just unset in the BEGIN block it seems there's a
> more fatal problem with 'nextfile' in rewind()...
>
> $ xgawk 'BEGIN{nextfile}'
> xgawk: error: `nextfile' used in BEGIN action
>
> Note: I've just xgawk at hand but suppose that error is inherited
> from gawk.

Calling rewind() in BEGIN is meaningless so it's
a good thing that you get an error message IMO.