Why does variable value change?

I don't have much experience with Perl, so I'm sure the problem is probably
pretty obvious to many of you.  But, when I run the following GCI script I
find the "if" tests on "loggedInCookie"/value and
"usernamePasswordPassedCookie"/value both pass the "if".  But, the last "if"
shows that both "havelogin" and "haveusernameandpassword" are "false".
What's going on here?

Thanks for any help,
Don

.
.
.
# Check to see if client has logged in and passed Username/Password test.
#
my @cookiepairs=split(/;/, $ENV{'HTTP_COOKIE'});
my ($pair, $name, $value, %cookie);
my $havelogin = 'false';
my $haveusernameandpassword = 'false';
foreach $pair (@cookiepairs)
{
($name, $value) = split(/=/, $pair);
if($name == 'loggedInCookie' and $value == 'true')
{
$havelogin = 'true';
}
if($name == 'usernamePasswordPassedCookie' and $value == 'true')
{
$haveusernameandpassword = 'true';
}
}
if($havelogin == 'false' or $haveusernameandpassword == 'false')
{
# html code will go here stating user not logged in.
exit;
}
#  Continue here if login is ok.
.
.
.


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Don <no@adr.com> wrote:
> I don't have much experience with Perl, so I'm sure the problem is
> probably pretty obvious to many of you.  But, when I run the following
> GCI script I find the "if" tests on "loggedInCookie"/value and
> "usernamePasswordPassedCookie"/value both pass the "if".  But, the last
> "if" shows that both "havelogin" and "haveusernameandpassword" are
> "false". What's going on here?

"==" compares it's arguments for numeric equality.  You want "eq", which
compares them for string equality.

>     if($havelogin == 'false' or $haveusernameandpassword == 'false')


Xho

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Don <no@adr.com> wrote:
> I don't have much experience with Perl, so I'm sure the problem is probabl
y
> pretty obvious to many of you.  But, when I run the following GCI script I
> find the "if" tests on "loggedInCookie"/value and
> "usernamePasswordPassedCookie"/value both pass the "if".  But, the last "i
f"
> shows that both "havelogin" and "haveusernameandpassword" are "false".
> What's going on here?

If you had enabled warnings (as guidelines for this group specifically
mention), the problem would have been made obvious.

Hint: String comparisons and numeric comparisons do not use the same
operator.

Axel

Axel wrote:

> Don <no@adr.com> wrote: 
>
> If you had enabled warnings (as guidelines for this group specifically
> mention), the problem would have been made obvious.
>
> Hint: String comparisons and numeric comparisons do not use the same
> operator.

Is the OP going to:

[1] enable warnings
[2] change the comparison
[3] both
[4] neither

:-D.

--
John                   Small Perl scripts: http://johnbokma.com/perl/
Perl programmer available:     http://castleamber.com/
Happy Customers: http://castleamber.com/testimonials.html

Don wrote:

>    # Check to see if client has logged in and passed Username/Password
>    test. #
>     my @cookiepairs=split(/;/, $ENV{'HTTP_COOKIE'});
>     my ($pair, $name, $value, %cookie);
>     my $havelogin = 'false';
>     my $haveusernameandpassword = 'false';

The problem with string constants as used here is that a typo can
introduce behaviour that will take you quite some time to pin down.

>     foreach $pair (@cookiepairs)
>     {
>         ($name, $value) = split(/=/, $pair);
>         if($name == 'loggedInCookie' and $value == 'true')
>         {
>             $havelogin = 'true';
>         }
>         if($name == 'usernamePasswordPassedCookie' and $value ==
>         'true') {
>             $haveusernameandpassword = 'true';
>         }
>     }
>     if($havelogin == 'false' or $haveusernameandpassword == 'false')
>     {
> # html code will go here stating user not logged in.
>         exit;
>     }
> #  Continue here if login is ok.

This code gives me the creepy feeling that anyone setting
usernamePasswordPassedCookie to true is logged in...

--
John                   Small Perl scripts: http://johnbokma.com/perl/
Perl programmer available:     http://castleamber.com/
Happy Customers: http://castleamber.com/testimonials.html

Don <no@adr.com> wrote:

> I don't have much experience with Perl,


Then you should ask for all the help you can get!


> so I'm sure the problem is probably
> pretty obvious to many of you.
^^^^^^

The problem is even obvious to a _machine_.

If you ask it to, the machine will tell you where your problem is...


> What's going on here?


You aren't working smart.


>         if($name == 'loggedInCookie' and $value == 'true')


You should always enable warnings when developing Perl code!


--
Tad McClellan                          SGML consulting
tadmc@augustmail.com                   Perl programming
Fort Worth, Texas

John Bokma <postmaster@castleamber.com> wrote: 
 
 

> Is the OP going to:
>
> [1] enable warnings
> [2] change the comparison
> [3] both
> [4] neither

Who knows? I am going to have a beer :)

Axel

On Sun, 24 Apr 2005 01:54:02 -0500, Axel <axel@white-eagle.invalid.uk>
wrote:

>Don <no@adr.com> wrote: 
>
>If you had enabled warnings (as guidelines for this group specifically
>mention), the problem would have been made obvious.
>
>Hint: String comparisons and numeric comparisons do not use the same
>operator.
>
>Axel
I have "use warnings" at the top of the module.  But, all I get is "500
server error" when I run the script on the server.

I changed the operators as suggested, but still get that error message, and
no warnings from Perl.

Don

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Don>    # Check to see if client has logged in and passed Username/Password 
test.
Don>    #
Don>     my @cookiepairs=split(/;/, $ENV{'HTTP_COOKIE'});

Please don't do this.  Use CGI.pm, and the "cookie" method there.
Otherwise, you will incorrectly declare an encoded value of "%74rue"
to be false, even though technically it's true.  (A browser could
choose to hexify every character of an incoming cookie at its
discretion.)

print "Just another Perl hacker,"; # the original!

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Don <no@adr.com> wrote:

> I have "use warnings" at the top of the module.  But, all I get is "500
> server error" when I run the script on the server.


Did you look in your server logs? That is where STDERR goes
for CGI programs.

Did you try running your program from the command line rather than
from the CGI environment?

Have you read the answser to your Frequently Asked Question already?

perldoc -q 500

My CGI script runs from the command line but not the browser.  (500
Server Error)

Have you checked out the Perl FAQs related to CGI programming with Perl?

perldoc -q CGI

Where can I learn about CGI or Web programming in Perl?

How can I get better error messages from a CGI program?


> I changed the operators as suggested, but still get that error message, an
d
> no warnings from Perl.


Show the code.

Show the messages.

We are not very good mind readers...


--
Tad McClellan                          SGML consulting
tadmc@augustmail.com                   Perl programming
Fort Worth, Texas