On Fri, 27 Sep 2002, waytech wrote:
> hi,
>
> i want to remove duplicate lines from one file(original file), and save
> the result to another file.
>
> the origianl file like this:
>
>
>--------------------------------------------------------------------------------------------
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
> [EMAIL PROTECTED]
>
>-------------------------------------------------------------------------------------------
>
> with each email address a line. I want to remove the duplicate
> lines(emais adresses) and
>
> save the result to a new file.
>
> I wrote a program , but it output nothing. can someome help ?
>
> Thanks a lot.
>
> kevin
>
>
>-------------------------------------------------------------------------------------------
> #!/usr/bin/perl -w
> #######################
> #Remove the duplicate line #
> #from a orginal file and save #
> #the result to a file. #
> #######################
> print "Enter the file that has duplicate lines.\n";
> $Dupli_file=<stdin>;
> chomp;
chomp by default works on $_, to chomp $Dupli_file you will have to say
chomp ($Dupli_file);
> print "The file you select is '$Dupli_file'\n";
> open (Dupli_file,"$Dupli_file");
When opening a file always check for failure like this
open (Dupli_file, $Dupli_file) or die "Cannot open $Dupli_file: $!\n";
$! will contain the error string. For more info on $! (perldoc perlvar)
> print "Please select the file you want to save the result to:\n";
> $Resu_file=<stdin>;
> chomp;
chomp ($Resu_file);
> print "The result file is $Resu_file\n";
> open (Resu_file,">$Resu_file");
Check for failure
> while (<Dupli_file>)
> {
> $orin_line=$_;
> while (<Resu_file>){
You are trying to read from a filehandle that has been opened for
writing. This will throw a warning message.
This logic will not work even if you open the result file for both reading
and writing. If the result file is empty to start with, the execution path
will never go into the while loop. while (<Resu_file>) will fail the first
time, which means nothing gets written into Resu_file. This makes it fail
again the 2'nd time, 3'rd time ...
> if("$_" eq "$orin_line")
> {
> next;
> }
> print Resu_file "$orin_line";
> };
> }
A hash is more suited for your job
#!/usr/bin/perl -w
use strict;
chomp (my $dupli_file = <STDIN>);
chomp (my $res_file = <STDIN>);
open (DUPLI, $dupli_file) or die "Failed to open $dupli_file: $!\n";
open (RESULT, ">$res_file") or die "Failed to open $res_file for writing: $!\n";
my %res_hash;
while (<DUPLI>) {
chomp;
unless ($res_hash{$_}++) {
print RESULT "$_\n";
}
}
close (DUPLI);
close (RESULT);
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