Re^3: shift vs @

Both ways are ok. $_[0] is actually ~~a reference~~ (thanks, tye!) an alias to the first argument passed by the caller. You can evaluate (or operate on) $_[0] directly. Passing arguments as references just adds another level of indirection.

You can also use prototypes for your subs and access your arguments inside the sub as references:

#!/usr/bin/perl
sub foo(\@\$) {
    warn "foo args: (".join(",",map{"'$_'"}@_).")\n";
    print "1st argument = $_[0]; content =("
         . join(',',map{"'$_'"} @{$_[0]}).")\n";
    print "2nd argument = $_[1]; content = '".${$_[1]}."'\n";
    my ($array,$scalar) = @_;
    push @$array, $$scalar;
    $$scalar = "blurf";
} 
my @ary = qw(foo bar baz);
my $foo = "blah";

foo(@ary,$foo);

print "ary: (@ary)\n";
print "foo: $foo\n";
[download]

output:

foo args: ('ARRAY(0x8167870)','SCALAR(0x8167978)')
1st argument = ARRAY(0x8167870); content =('foo','bar','baz')
2nd argument = SCALAR(0x8167978); content = 'blah'
ary: (foo bar baz blah)
foo: blurf
[download]

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

Comment on Re^3: shift vs @_ Select or Download Code

Replies are listed 'Best First'.
Re^4: shift vs @_ (alias) by tye (Sage) on Oct 03, 2006 at 21:26 UTC
`$_[0]` is actually a reference to the first argument passed by the caller. I'm sure you know what you meant, but... `$_[0]` is (usually) an alias to the first argument. If it were a reference then you'd have to use `${$_[0]}` or such. - tye	[reply] [d/l] [select]


good chemistry is complicated, and a little bit messy -LW
	PerlMonks

Re^3: shift vs @_