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Basic debugging checklist

by toolic (Bishop)
on Feb 23, 2009 at 00:06 UTC ( #745674=perltutorial: print w/ replies, xml ) Need Help??

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  1. or download this
    use strict;
    use warnings;
    use diagnostics;
    
  2. or download this
    warn "$var\n";
    print "@things\n";   # array with spaces between elements
    
  3. or download this
    chomp $var;
    print ">>>$var<<<\n";
    
  4. or download this
    my $copy = $str;
    $copy =~ s/([^\x20-\x7E])/sprintf '\x{%02x}', ord $1/eg;
    print ":$copy:\n";
    
  5. or download this
    use Data::Dumper;
    print Dumper(\%hash);
    print Dumper($ref);
    
  6. or download this
    print ref $ref, "\n";
    
  7. or download this
    $ perl -MO=Deparse -p program.pl
    
  8. or download this
    open my $fh, '<', 'foo.txt' or die "can not open foo.txt: $!";
    
  9. or download this
    if (system $cmd) {
        print "Error: $? for command $cmd"
    ...
        print "Command $cmd is OK"
    }
    $out = `$cmd`; print $? if $?;
    
  10. or download this
    eval { do_something() }; warn $@ if $@;
    
  11. or download this
    use Carp qw(cluck);
    cluck("var is ($var)");
    
  12. or download this
    $ perl -MCarp::Always program.pl
    
  13. or download this
    # what the heck does /^\s+$/ mean?
    use YAPE::Regex::Explain;
    print YAPE::Regex::Explain->new('/^\s+$/')->explain();
    
  14. or download this
    use WWW::Mechanize;
    if ($mech->success()) { ... }
    

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