Re^2: Question on File Handler and Subroutines in Perl

Hi tobyink,

Ah yes, you are right. It keeps getting stuck at the file a.txt and printing only the contents out from it. :( Now I know why. It's because of the "\n". I will read up what chomp does. Thank you for the hint! :) The book "Learn Perl the Hard Way" really lives up to its name. Haha. Oh dear.

Ah yes, I realized that "my $file = scalar(@_)" isn't doing anything too after debugging it yesterday. Thank you for pointing it out. Just wondering, does that statement convert an array "stream" into a scalar quantity, e.g. a string?

Thank you (:

Comment on Re^2: Question on File Handler and Subroutines in Perl

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Re^3: Question on File Handler and Subroutines in Perl by hippo (Archbishop) on Mar 06, 2019 at 09:01 UTC
Just wondering, does that statement convert an array "stream" into a scalar quantity, e.g. a string? Yes, but not the scalar quantity you might imagine. Running scalar on an array ~~or list~~ argument returns the number of elements in the array ~~or list~~ as this is what happens when an array ~~a list~~ is evaluated in scalar context. Conversely, if you wanted a string which was a concatenation of all the elements in the array then you might use join. `#!/usr/bin/env perl use strict; use warnings; my @foo = ('dog', 'bites', 'man', 'bites', 'dog'); printf "scalar = '%s'\n", scalar @foo; printf "join = '%s'\n", join ' ', @foo;` [download] Update: removed erroneous mentions of lists as their behaviour in scalar context differs from arrays (returns the last item). Thanks choroba for reminding me of this.	[reply] [d/l]

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Re^3: Question on File Handler and Subroutines in Perl
by hippo (Archbishop) on Mar 06, 2019 at 09:01 UTC

Just wondering, does that statement convert an array "stream" into a scalar quantity, e.g. a string?

Yes, but not the scalar quantity you might imagine. Running scalar on an array ~~or list~~ argument returns the number of elements in the array ~~or list~~ as this is what happens when an array ~~a list~~ is evaluated in scalar context. Conversely, if you wanted a string which was a concatenation of all the elements in the array then you might use join.

#!/usr/bin/env perl 
use strict;
use warnings;

my @foo = ('dog', 'bites', 'man', 'bites', 'dog');
printf "scalar = '%s'\n", scalar @foo;
printf "join = '%s'\n",   join ' ', @foo;
[download]

Update: removed erroneous mentions of lists as their behaviour in scalar context differs from arrays (returns the last item). Thanks choroba for reminding me of this.

[reply]
[d/l]