Why do I get a blank page from my Perl CGI script?
- by Jason
The user enters a product code, price and name using a form. The script then either adds it to the database or deletes it from the database. If the user is trying to delete a product that is not in the database they get a error message. Upon successful adding or deleting they also get a message. However, when I test it I just get a blank page. Perl doesnt come up with any warnings, syntax errors or anything; says everything is fine, but I still just get a blank page.
The script:
#!/usr/bin/perl
#c09ex5.cgi - saves data to and removes data from a database
print "Content-type: text/html\n\n";
use CGI qw(:standard);
use SDBM_File;
use Fcntl;
use strict;
#declare variables
my ($code, $name, $price, $button, $codes, $names, $prices);
#assign values to variables
$code = param('Code');
$name = param('Name');
$price = param('Price');
$button = param('Button');
($code, $name, $price) = format_input();
($codes, $names, $prices) = ($code, $name, $price);
if ($button eq "Save") {
add();
}
elsif ($button eq "Delete") {
remove();
}
exit;
sub format_input {
$codes =~ s/^ +//;
$codes =~ s/ +$//;
$codes =~ tr/a-z/A-Z/;
$codes =~ tr/ //d;
$names =~ s/^ +//;
$names =~ s/ +$//;
$names =~ tr/ //d;
$names = uc($names);
$prices =~ s/^ +//;
$prices =~ s/ +$//;
$prices =~ tr/ //d;
$prices =~ tr/$//d;
}
sub add {
#declare variable
my %candles;
#open database, format and add record, close database
tie(%candles, "SDBM_File", "candlelist", O_CREAT|O_RDWR, 0666)
or die "Error opening candlelist. $!, stopped";
format_vars();
$candles{$codes} = "$names,$prices";
untie(%candles);
#create web page
print "<HTML>\n";
print "<HEAD><TITLE>Candles Unlimited</TITLE></HEAD>\n";
print "<BODY>\n";
print "<FONT SIZE=4>Thank you, the following product has been added.<BR>\n";
print "Candle: $codes $names $prices</FONT>\n";
print "</BODY></HTML>\n";
} #end add
sub remove {
#declare variables
my (%candles, $msg);
tie(%candles, "SDBM_File", "candlelist", O_RDWR, 0)
or die "Error opening candlelist. $!, stopped";
format_vars();
#determine if the product is listed
if (exists($candles{$codes})) {
delete($candles{$codes});
$msg = "The candle $codes $names $prices has been removed.";
}
else {
$msg = "The product you entered is not in the database";
}
#close database
untie(%candles);
#create web page
print "<HTML>\n";
print "<HEAD><TITLE>Candles Unlimited</TITLE></HEAD>\n";
print "<BODY>\n";
print "<H1>Candles Unlimited</H1>\n";
print "$msg\n";
print "</BODY></HTML>\n";
}
