Hi George,
Perldoc -f shift gives you:
=item shift ARRAY
=item shift
Shifts the first value of the array off and returns it, shortening the
array by 1 and moving everything down. If there are no elements in the
array, returns the undefined value. If ARRAY is omitted, shifts the
C<@_> array within the lexical scope of subroutines and formats, and the
C<@ARGV> array at file scopes or within the lexical scopes established
by
the C<eval ''>, C<BEGIN {}>, C<END {}>, and C<INIT {}> constructs.
See also C<unshift()>, C<push()>, and C<pop()>. C<Shift()> and
C<unshift()> do
the
same thing to the left end of an array that C<pop()> and C<push()> do
to the
right end.
This basically means that if you are inside a subroutine it defaults to
@_ and @ARGV if you are not in a subroute (the perl equiv of C's
main()).
That's the way I read it anyway.
Which means (based on what you said) that the book must be wrong as @_
doesn't work while @ARGV does.
Gary.
On Monday 04 June 2001 9:02 pm, George Petri wrote:
> Hi!
>
> In a book called "Open Source Linux Web Porgramming" by Jones and
> Batchelor, it says (on Page 61):
>
> "When you launch a script from the command line, for example, @_
> populates with all of the parameters passed in through the command
> line. The shift function, among others, will use @_ by default if no
> other array is provided.
>
> #!/usr/bin/perl
> @firstCommandLineArg=shift;
> @secondCommandLineArg=shift;"
>
> The provided code snipplet works but if I use "shift @_" (since @_ is
> supposedly used by default anyway), I do not get the command line
> arguments.
>
> However, if I use "shift @ARGV", I DO get the command line arguments.
> If the shift function really does use @_ as its default argument,
> then why did shift in the example code, use @ARGV as default? Does
> @_ really get populated "with all of the parameters passed in through
> the command line"?
>
> Thanks,
> George Petri
--
Gary Stainburn
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