Solved

Strange problem .. Help

Posted on 2000-04-17
3
170 Views
Last Modified: 2010-03-05
Hi folks,

I am facing a strange problem. I would appreciate if u can help me finding what I am doing wrong. I am writing a cgi program using CGI.pm. I am reading a parameter value by executing GET from the browser and executing a query with the value.

It is like http://myserver/cgi-bin/test.cgi?contactID='CT0001'

My program looks like,

/****************************************
$myCgi = new CGI;
$contactId = $myCgi -> param('contactID');
chomp($contactId);
# if contact id is empty, show error message and return
if($contactId == "")
{
        Util::showError("Contact ID $contactId cannot be blank");
        exit ;
}
*******************************************

So here I am checking whether the value is passed or not.  Initially the contact id field was numeric and I used to pass

http://myserver/cgi-bin/test.cgi?contactID=001

It used to work fine, but when I started sending CT0001, it executes the showError routine even though I have passed contact Id properly. Even in the showError subroutine, I am trying to print the $contactId, it is printing properly as CT0001. But logically, it should not execute the showError subroutine.

What am I doing wrong here ?? Is ( if ( $contactId == "") is not a valid check for empty string value ?? Why it is working for numeric and not alphanumeric ??

Thanx in advance,
Maha


0
Comment
Question by:maha
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 16

Accepted Solution

by:
maneshr earned 10 total points
ID: 2723253
you are using the == operator which is meant for Numeric comparison NOT String comparison.

Replace == with eq and it should work.

== != <=> (equal to, not equal to, signed comparison)

eq ne cmp (their string equivalents)

An even better option would be to use regular expression. That way you dont have to worry about string or numbers.

Eg

## Check if contactId is empty or if the user has entered white spaces!!
if($contactId=~ /^$/ || $contactId=~ /^\s+$/){

.....

}
0
 

Author Comment

by:maha
ID: 2723327
Thanx Maneshr

Actually I found the solution ( use of eq) and it worked. So I did delete this question . I donot understand how it has reappeared again. ANyway thanx for your time and so I accept your answer.

I am new to perl and learning it as I use. Can u recommend good book for regular expressions in perl ??

Maha
0
 
LVL 16

Expert Comment

by:maneshr
ID: 2723388
Glad to be of help to you.

i would suggest you start with...

Learning Perl, 2nd Edition

By Randal L. Schwartz & Tom Christiansen Foreword by Larry Wall
2nd Edition July 1997
1-56592-284-0, Order Number: 2840
302 pages, $29.95

you can get better deals if you search on the NET.

======================
Specifically for Regular Expressions you can use...

Mastering Regular Expressions

Powerful Techniques for Perl and Other Tools

By Jeffrey E. F. Friedl
1st Edition January 1997
1-56592-257-3, Order Number: 2573
368 pages, $34.95

you can get the Table of Contents at ...
http://www.oreilly.com/catalog/regex/toc.html

Hope that helps
0

Featured Post

[Webinar] Learn How Hackers Steal Your Credentials

Do You Know How Hackers Steal Your Credentials? Join us and Skyport Systems to learn how hackers steal your credentials and why Active Directory must be secure to stop them. Thursday, July 13, 2017 10:00 A.M. PDT

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I have been pestered over the years to produce and distribute regular data extracts, and often the request have explicitly requested the data be emailed as an Excel attachement; specifically Excel, as it appears: CSV files confuse (no Red or Green h…
Checking the Alert Log in AWS RDS Oracle can be a pain through their user interface.  I made a script to download the Alert Log, look for errors, and email me the trace files.  In this article I'll describe what I did and share my script.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
Six Sigma Control Plans

691 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question