Anirban Adhikary wrote:
> Dear List
> I have write the The following code to check a file and print only distinct
> lines to a new file and skips the duplicate lines. My source file is as
> follows
>
> hello how are you?
> hello how are you?
> What language did you want to use?
> What language did you want to use?
> I am here
> You are there
> this is my first perl script
> What language did you want to use?
>
> ###############################################################################
> my code is as follows
>
>
> #use strict;
> #use warnings;
Never comment out these lines - they help enormously to find simple errors.
> print "Enter the Absolutepath of the file\t";
> my $input=<STDIN>;
> chomp($input);
>
> dup($input);
>
> sub dup
> {
> my $filename=shift;
> my $count=0;
> my @arr;
> my $el;
> my $element;
- Variables should be declared as close as possible to their point of first use.
- Try to use meaningful variable names; the @ in @arr means 'array' so you have
something called "array arr". Also the difference between the function of $el
and $element isn't clear from their names.
> open(FH,"$filename");
> while(<FH>)
- You must always check whether a file open succeeded.
- $filename should stand on its own. Read the perlfaq article
perldoc -q quoting
entitled What's wrong with always quoting "$vars"?
- The three-parameter form of open and lexical file handles are preferred, like
this
open my $fh, '<', $filename or die $!;
while (<$fh>) {
> {
> chomp($_);
> $element = $_;
> if($count ==0)
> {
> push(@arr,$element);
> $count+=1;
> print "Count is $count\n";
$count isn't a count, as it is only incremented when it is zero and never used
thereafter. You also don't need it at all, so you can remove this if statement
altogether.
> }
> else
> {
> foreach $el(@arr)
> {
> my $len=$#arr;
$len is the index of the last element of @arr, not its length. Use
my $len = @arr;
to get that.
> chomp($el);
The strings were chomped before they were added to @arr so there is no need to
do it again.
> # print "$element\n";
> #print "The length of arr is $len\n";
> if($el == $element)
The == operator is for comparing numbers; to compare strings you must use
eq. This is why your elsif block wasn't being executed: the values are being
forced to numbers before they are compared, and since non-numeric strings
evaluate as zero they were always numerically equal.
If you had left warnings enabled you would have a message to tell you this.
> {
> print "\t######Inside If######\t\n";
> print $element."\n";
> next;
> #push(@arr,$_);
> }
>
> elsif($el != $element)
There is no need to test again. If
$el eq $element
failed, then
$el ne $element
must succeed, and you need only an 'else' here.
> {
> push(@arr,$element);
You shouldn't modify an array that you're currently iterating over, as the
results aren't guaranteed and anything may happen. In other words, don't write
foreach (@arr) {
:
push @arr, $val;
:
}
> print "\t########Inside Elseif\n";
> #next;
> }
> }
> }
- The braces aren't paired properly in your program. I presume an extra one
belongs here.
- You test each new line again /every/ element in @arr, and push the line onto
the array /every time/ it finds an array element that doesn't match. I assume
you want to push the new line onto the array only if none of the elements match?
Something like this perhaps
while (my $element = <$fh>) {
chomp $element;
my $found;
foreach my $el(@arr) {
if ($el eq $element) {
$found++;
last;
}
}
if (not $found) {
print "$element\n";
push @arr,$element;
}
}
> }
>
> ###############################################################
> The problems I am facing are
>
> 1) The code is not getting entered into elsif block
>
> 2) I am comparing between 2 strings but if I use "eq" or "ne" for
> comparison I am getting some horrible output so I am using numeric
> comparison.
>
> 3)If I am giving print the $element variable outside foreach loop it is
> getting printed but Inside foreach loop it is not showing anything.
>
> Can anybody Please suggest me where I am making the mistake?
HTH,
Rob
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