Perl - how to avoid warnings about uninitialized elements of an array? - arrays

Question

#!/usr/bin/perl
use strict;
use warnings;
sub paragraph
{
open my $file, "<", "dict.txt" or die "$!";
my #words = <$file>;
close $file;
print "Number of lines:";
my $lines = <>;
print "Max words per line:";
my $range = <>;
for(my $i = 0; $i<$lines; $i++){
my $wordcount = int(rand($range));
for(my $s = 0; $s<=$wordcount; $s++){
my $range2 = scalar(#words);
my $word = int(rand($range2));
print $words[$word]." ";
if($s==$wordcount){
print "\n";}
}
}
}
paragraph;
I'm trying to learn programming, so I just wrote this simple script.
When running this code, I am getting use of uninitialized value errors... I can't figure out why, but I sure I am just overlooking something.

Answer 1

These two lines open the dict.txt file for writing and then try to read from it.
open FILE, ">dict.txt" or die $!;
my #words = <FILE>;
Since you can't read from a write-only file, it fails. If the file was writable, then it is empty now - sorry about your nice word list. Suggestion:
open my $file, "<", "dict.txt" or die "$!";
my #words = <$file>;
close $file;
Also, please learn to indent your braces in an orthodox fashion, such as:
sub go
{
print "Number of lines:";
my $lines = <>;
print "Max words per line:";
my $range = <>;
for (my $i = 0; $i<$lines; $i++){
my $wordcount = int(rand($range));
for (my $s = 0; $s<$wordcount; $s++){
my $range2 = 23496;
my $word = int(rand($range2));
my $chosen = #words[$word];
print "$chosen ";
if ($s=$wordcount){
print "\n";
}
}
}
}
Also leave a space between 'if' or 'for' and the open parenthesis.
Your assignment if ($s = $wordcount) probably isn't what you intended; however, the condition if ($s == $wordcount) will always be false since it is in the scope of a loop with the condition $s < $wordcount. You need to rethink that part of your logic.
On average, you should choose a better name for your function than go. Also, it is probably better to invoke it as go();.
When I test compile your script, Perl warns about:
Scalar value #words[$word] better written as $words[$word] at xx.pl line 19.
You should fix such errors before posting.
You have:
my $range2 = 23496;
my $word = int(rand($range2));
Unless you have more than 23,496 words in your dictionary, you will likely be accessing an uninitialized word. You should probably use:
my $range2 = scalar(#words);
That then just leaves you with some logic problems to resolve.
Given 'dict.txt' containing:
word1
word2
word3
word4
nibelung
abyssinia
tirade
pearl
And 'xx.pl' containing:
#!/usr/bin/env perl
use strict;
use warnings;
open my $file, "<", "dict.txt" or die $!;
my #words = <$file>;
close $file;
sub go
{
print "Number of lines: ";
my $lines = <>;
print "Max words per line: ";
my $range = <>;
my $range2 = scalar(#words);
for (1..$lines)
{
for (1..$range)
{
my $index = int(rand($range2));
my $chosen = $words[$index];
chomp $chosen;
print "$chosen ";
}
print "\n";
}
}
go();
When I run it, I get:
$ perl xx.pl
Number of lines: 3
Max words per line: 4
word4 word3 word4 nibelung
abyssinia pearl word1 tirade
word3 word1 word3 word2
$

Answer 2

Some more bugs:
if($s=$wordcount){
You need == here.