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A question about a sample script.

King Norre
Novice

Apr 15, 2003, 6:07 AM

Post #1 of 7 (577 views)

A question about a sample script.	Can't Post

Hi,

I'm learning Perl using the book "Teach yourself Perl5 in 21 days" from David Till.
Somewhere in the book there's the following sample script:

#!/usr/bin/perl
# a word-counting program that uses the NEXT statement

$total = 0;
while ($line = <STDIN>) {
$line =~ s/^[\t ]*//;
$line =~ s/[\t ]*\n$//;
next if ($line eq "");
@words = split(/[\t ]+/, $line);
$total += @words;
}
print ("The total number of words is $total\n");

---------- END

Normally the input should end when I press CTRL + D.
However, when I run the script I can only put in 1 line.
When I press ENTER I get the following error message:

Split loop at ./ex8.11 line 9, <STDIN> line 1.

I have absolutely NO idea what could be wrong.
Can anyone help me?
Thanks in advance,

KN

davorg
Thaumaturge / Moderator

Apr 15, 2003, 6:57 AM

Post #2 of 7 (575 views)

Re: [King Norre] A question about a sample script. [In reply to]	Can't Post

I just cut and pasted that code and it worked straight off as expected.

The book you mention is rather old and has a reputation in the Perl community of not being very good. The code you quote contains a number of bad practices. I'd recommend getting rid of it and replacing it with a better book.

Try replacing your code with something like this:

Code

#!/usr/bin/perl 
# a word-counting program that uses the NEXT statement 
 
use strict; 
use warnings; 
 
my $total = 0; 
while (<STDIN>) { 
  s/^\s+//; 
  s/\s+$//; 
  next unless $_; 
  my @words = split(/\s+/, $_); 
  $total += @words; 
} 
print ("The total number of words is $total\n");

--
Dave Cross, Perl Hacker, Trainer and Writer
http://www.dave.org.uk/
Get more help at Perl Monks

King Norre
Novice

Apr 15, 2003, 7:20 AM

Post #3 of 7 (574 views)

Re: [davorg] A question about a sample script. [In reply to]	Can't Post

Hey thanks for the advice Dave. The code you gave me works.
I've been looking for some books about Perl.
Is "Learning Perl, 3rd edition" from O'Reilly a good/better book to start with?

KN

davorg
Thaumaturge / Moderator

Apr 15, 2003, 7:29 AM

Post #4 of 7 (572 views)

Re: [King Norre] A question about a sample script. [In reply to]	Can't Post

Every Perl installation comes complete with the Perl FAQ which has answers to all sorts of interesting questions about Perl. You should really read it. It includes a list of recommended Perl books.

perldoc perlfaq2

--
Dave Cross, Perl Hacker, Trainer and Writer
http://www.dave.org.uk/
Get more help at Perl Monks

Paul
Enthusiast

Apr 15, 2003, 7:37 AM

Post #5 of 7 (570 views)

Re: [davorg] A question about a sample script. [In reply to]	Can't Post

Quote

s/^\s+//;
s/\s+$//;
next unless $_;
my @words = split(/\s+/, $_);

or:

Code

s/^\s+|\s+$//g;    
next unless $_;    
my @words = split /\s+/;

(This post was edited by Paul on Apr 15, 2003, 7:38 AM)

davorg
Thaumaturge / Moderator

Apr 15, 2003, 7:44 AM

Post #6 of 7 (565 views)

Re: [Paul] A question about a sample script. [In reply to]	Can't Post

Quote

Code

my @words = split /\s+/;

or even just

Code

my @words = split;

--
Dave Cross, Perl Hacker, Trainer and Writer
http://www.dave.org.uk/
Get more help at Perl Monks

Paul
Enthusiast

Apr 15, 2003, 8:30 AM

Post #7 of 7 (563 views)

Re: [davorg] A question about a sample script. [In reply to]	Can't Post

Exactly, wasn't so hard was it =)

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