subroutine call 1

[rjtayl27]

$copy(\@x,\@y,$size);
I am having trouble copying the contents of @x into @y

 

[thenewa2x]

1.) sub-routines don't use the dollar sign, it's the ampersand: &
2.) copy isn't a standard function.

if you want to copy an array in PERL

@x = @y;

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If you helped... thx.

 

[mikevh]

The ampersand is rarely needed on subroutine calls in modern Perl. It was required in Perl 4. From perlsub:

To call subroutines:

NAME(LIST); # & is optional with parentheses.
NAME LIST; # Parentheses optional if predeclared/imported.
&NAME(LIST); # Circumvent prototypes.
&NAME; # Makes current @_ visible to called subroutine.

Check out perldoc perlsub for the full lowdown.

 

[thenewa2x]

it's required if you have strict enabled though.

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If you helped... thx.

 

[mikevh]

Nope. I use strict all the time, rarely put & on a subroutine call. Can you point me to something that says I should?

 

[Geekatron]

All four syntaxes listed by Mike are valid with or without strict enabled.

What is NOT allowed with strict enabled is calling a sub with NEITHER & nor ():

use strict;
go;
exit;

sub go {
  print "wibble!\n";
}

In this example Perl will complain bitterly:

Bareword "go" not allowed while "strict subs" in use at x line 3.
Execution of x aborted due to compilation errors.

Perl complains because using a bareword function call is ambiguous - Perl has to guess whether "go" is supposed to be a function call, a scalar, etc. Strict doesn't allow such guessing.

--G
(who has nothing else to do on a Friday night - pitiful, just pitiful)

 

[mikevh]

If the sub body or just a declaration occurs before the call, it's still okay, even without & or (). Both of the following work.

#!perl
use strict;
use warnings;

sub go {
  print "wibble!\n";
}

go;
exit(0);

#!perl
use strict;
use warnings;

sub go;

go;
exit(0);

sub go {
  print "wibble!\n";
}

 

[uida1154]

Wonder where the $size is used for?

 

[thenewa2x]

thanks for the star!!

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If you helped... thx.