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Perl Programming – Appendix

Perl Programming – Appendix. There ’ s more than one way to do it Keep easy things easy and the hard possible. Problem 1: Regex Example. $_ = “ this is a test”; /(w+)W+(w+)/; # match first two words, # $1 = “this”, $2 = “is” print “$1, $2<br>”;. $_ = “ this is a sample string ”;

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Perl Programming – Appendix

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  1. Perl Programming – Appendix There’s more than one way to do it Keep easy things easy and the hard possible

  2. Problem 1: Regex Example $_ = “this is a test”; /(\w+)\W+(\w+)/; # match first two words, # $1 = “this”, $2 = “is” print “$1, $2\n”; $_ = “this is a sample string”; /sa.*le/; # $` = “this is a ” # $& = “sample” # $’ = “ string”

  3. Regex Example: Date Extraction • #!/usr/bin/perl • $date = `date`; • print "$date"; # 2008年 2月29日 周五 11時27分16秒 CST • $date =~ /^(\d+)\D+(\d+)\D+(\d+)\S+\s+周(\S+)/; • %hash = ( year => $1, month => $2, day => $3, weekday => $4, • ); • for (keys %hash) { • print "$_ => $hash{$_}\n"; • }

  4. One-Line Perl Execution

  5. File Name Access Mode Flags Problem 2: File Handler • An interface to file access • File handler in C • File handler in Perl Read, write User File Handler FILE *fp = fopen("count.dat","r"); fgets(numb, 8, fp); open FH, “count.dat” or die “open file failure: $!”; $numb = <FH>;

  6. Problem 3: <> • while (<>) { print } • Using diamond operator <> • Get data from files specified on the command line • $ARGV records the current filename • @ARGV shifts left to remove the current filename • Otherwise read from STDIN • while (<FH>) { print } • Read from file handler FH

  7. CPAN • If you see similar errors on execution of perl… • Your @INC is incorrect, or • You need to install the required modules • We can install modules from command line tool • cpan • Useful tool to install modules in CYGWIN

  8. On the first use we should set up configuration <Enter>

  9. <Enter> <Enter>

  10. Keep <ENTER>…

  11. Change PREFIX! PREFIX is where to install your modules. If you don’t understand, <ENTER> For non-root users, my setting is ~/perl/module/ Still keep <ENTER> until…

  12. Select the nearest CPAN site 2

  13. Install desired modules: After installation, type “quit” to leave cpan

  14. Some Useful Built-in • system "tail -20 $ENV{HOME}/mail/procmail.log"; • exec “rm -f file”; • sleep 3; • select undef, undef, undef, 3; • $char = getc ; • perl -e 'system("stty raw");getc‘ • exit 1; • die “error msg: $!”; # sleep 3 seconds # need to wait ENTER # immediate return on keystroke

  15. Demo: Pdir, BBS like directory handler

  16. Demo: Process Killer

  17. Demo: wxPerl + OpenGL

  18. Demo: Kephra using wxPerl on Windows

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