in reply to How to gracefully deal with a regex problem

Put eval { } around the part that dies and then check $@. If $@ is set, then you averted a nasty death and can refuse to put the value into the database.

Even more reliable is: 

    if(  ! eval { ...; 1 }  ) {
        warn "Invalid value ($@)...";
    }

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since pathelogical cases can set $@ even though the code succeeded.

Checking other responses, I notice \Q being suggested. Let me just add that if that works for you then you might want to consider using index() instead of a regex.

        - tye (but my friends call me "Tye")

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Re: (tye)Re: How to gracefully deal with a regex problem
by michellem (Friar) on Mar 07, 2001 at 02:22 UTC
    How would I use index() in this situation? Check for the presence of particular problematic characters?

    The regex I'm using, as I clarified above isn't really a test per se - it's a part of the script which allows users to edit their data - using the form page as a template, and replacing particular lines in the HTML code with values they entered in the first place. Maybe there are better ways to do it than the following: 

    #Read in the template HTML file with the form
.
    $form_file = $fields{formpage};

    open (FILE, "$form_file");
    @form = <FILE>;

    $select_flag=0;

    foreach (@form) {
    foreach $key (keys %fields) {
        if ($_ =~ /name=\"$key\"/i) {
        if (($key ne "table")&&($key ne "formpage")&&($key ne "dbname"
+)&&($_ !~ /meta/i)) {
            if ($_ =~ m/check|radio/i) {
            $valueplace = index($_, "value=");
            $value = substr($_,$valueplace+7);
            ($value,$junk) = split(/\"/,$value);
            if ($fields{$key} eq $value) {
                $_ =~ s/input/input checked/i;
               print; print "\n"; $form_flag=1; last;
            }
            next;
            } elsif ($_ =~ /textarea/i) {
  #these are the regex giving me trouble if the data has wierd charact
+ers

            $_ =~ s/><\/textarea/>$fields{$key}<\/textarea/i;
            } elsif ($_ =~ m/select/i) {
            } else {
            $_ =~ s/input/input value=\"$fields{$key}\"/i;
            }
            print; print "\n";
            $form_flag = 1;

        }
            } elsif ($_ =~ /select/) {
                $select_flag=1;
            } elsif (($select_flag)&&($_ =~ m/option value=/i)) {

                $_ =~ s/option value=\"$fields{$key}\"/option value=\"
+$fields{$key}\" selected/;;
        }

         }
    if (!$form_flag) {
        print; print "\n"; next;
    } else {$form_flag=0; next;}
    }

}

    [download]
    BTW, this script doesn't entirely work the way I'd like it to. For some reason, it can't seem to do the menu selection right. Otherwise, it works pretty well.
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[d/l]

      Well, I wasn't thinking of the right-hand part of a regex because: 

      $problem= "[";
$str= "(input)";
$str =~ s/input/input value="$problem"/;
print "<$str>\n";
# produces <(input value="[")>

      [download]

      So I don't see how your original problem matches this problem.

      I was thinking of the fact that people surprisingly often write $str =~ /\Q$sub\E/ instead of index($str,$sub).

      Now that you give us more information, it looks to me like you need to be using CGI.pm which will know how to escape your parameter values properly.

              - tye (but my friends call me "Tye")
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[d/l]
[select]

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