Thanks for your kindly suggestion, you help me learn more of perl knowledge.
-----Original Message----- From: Shlomi Fish [mailto:shlo...@shlomifish.org] Sent: Friday, February 06, 2015 4:45 PM To: beginners@perl.org Subject: Re: use perl format data Hi Mr./Ms. Wang, a few notes on your code. On Fri, 6 Feb 2015 02:53:52 +0000 "Wang, Zeng-Sheng (TS-GSD-China-ZZ)" <zengsheng.w...@hp.com> wrote: > Dear Uri, > > First thanks for your kindly help and a read-friendly instruction, I > will not use $a and $b for variables. According to your explanation, I > finish the code as below: First of all, next time - do not include the line numbers when showing the code because it makes copy+paste more difficult. > #!/usr/bin/perl -w 2 use strict; Don't use the "-w" flag - use "use warnings;" instead: http://perl-begin.org/tutorials/bad-elements/#the-dash-w-flag > 3 open(FH,'<',"file1"); Don't use bareword filehandles and either add "use autodie;" or throw an exception on open: http://perl-begin.org/tutorials/bad-elements/#open-function-style > 4 my @first_file = <FH>; > 5 close (FH); > 6 > 7 open(FH,'<',"file2"); > 8 my @second_file = <FH>; > 9 close (FH); > 10 > 11 open(FH,'<',"file3"); > 12 my @third_file = <FH>; > 13 close (FH); > 14 > 15 chomp @first_file; > 16 chomp @second_file; > 17 chomp @third_file; @first_file, @second_file, and @third_file really should be an array of arrays. See: http://perl-begin.org/topics/references/ > 18 > 19 my ($out_line,$number); > 20 $number = @first_file; > 21 $out_line=''; Please do not predeclare variables: http://perl-begin.org/tutorials/bad-elements/#declaring_all_vars_at_top > 22 for(0..$number){ You have an off by one error here. > 23 $out_line.= shift @first_file; > 24 $out_line.= "\t".shift @second_file; > 25 $out_line.="\t".shift @third_file; > 26 $out_line.="\n";} This should really be done using join. > 27 > 28 print $out_line; > > I realize my target, however, there are some warnings in the prompt, > how can I eliminate them? Why? perl format.pl Use of uninitialized > value in concatenation (.) or string at format.pl line 23. Use of > uninitialized value within @second_file in concatenation (.) or string > at format.pl line 24. Use of uninitialized value within @third_file in > concatenation (.) or string at format.pl line 25. Maybe the arrays are of different lengths. Regards, Shlomi Fish -- ----------------------------------------------------------------- Shlomi Fish http://www.shlomifish.org/ UNIX Fortune Cookies - http://www.shlomifish.org/humour/fortunes/ There is no IGLU Cabal! Its members can be arranged in N! orders to form N! different Cabals. The algorithm to find which order formulates the correct IGLU Cabal is NP‐Complete. Please reply to list if it's a mailing list post - http://shlom.in/reply . -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
