Question

Work around changing const C++

Asked by: czlong

Existing code uses const in getDBPassword function to get password from an ini file.  I need to decrypt that password value but because the existing code uses const the value never changes.  
What is a (if any) work around to this without totally re-writing the new class?  Can the existing below function getDBPassword or setDBPassword be modified to accommodate my problem? How?

This is the existing implementation that gets cleartext PW: setDBPassword(iniFile.getDBPassword());

const _bstr_t & getDBPassword() const
      {
            return bstrDBPassword;
      }
      
      
void setDBPassword(_bstr_t newDBPassword)
      {                                           
            bstrDBPassword = newDBPassword;          
      }      
      
 My decrypt implementation: decrypt(newDBPassword, pKey);
 
 decrypt(char *pCode, const char *pKey)

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-10-20 at 12:42:01ID24828253
Topics

C++ Programming Language

,

Microsoft Visual C++

Participating Experts
3
Points
500
Comments
9

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

    Free Tech Articles

    1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
      It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
    2. SCCM OSD Basic troubleshooting
      SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
    3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
      This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
    4. Create a Win7 Gadget
      This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
    5. Outlook continually prompting for username and password
      There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
    6. Backup Exchange 2010 Information Store using Windows Backup
      There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

    Cloud Class Webinars

    1. Avoiding Bugs in Microsoft Access
      Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
    2. Top 10 Best New Features in Visio 2010
      Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
    3. IT Consultant Business Secrets Revealed
      Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
    4. Disaster Recovery and Business Continuity
      Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
    5. Organize Your Visio Diagrams with Containers and Lists
      Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
    6. How to Us Objects, Properties, Events and Methods in Microsoft Access
      Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

    Join the Community

    Give a Little. Get a Lot.

    Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

    Join the Community

    Answers

     

    by: jkrPosted on 2009-10-20 at 13:07:46ID: 25617994

    Why not using a 'const_cast()' (http://www.cppreference.com/wiki/keywords/const_cast), e.g.

    setDBPassword(const_cast<_bstr_t>(iniFile.getDBPassword()));

                                              
    1:

    Select allOpen in new window

     

    by: jkrPosted on 2009-10-20 at 13:09:09ID: 25618006

    BTW, more about how these casts work at http://www.cplusplus.com/doc/tutorial/typecasting/ 

    // const_cast
#include <iostream>
using namespace std;
 
void print (char * str)
{
  cout << str << endl;
}
 
int main () {
  const char * c = "sample text";
  print ( const_cast<char *> (c) );
  return 0;
}

                                              
    1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:

    Select allOpen in new window

     

    by: evilrixPosted on 2009-10-20 at 13:35:19ID: 25618274

    It returns a const reference but there's nothing to stop you taking a non-const copy is there?

     

    by: Infinity08Posted on 2009-10-20 at 14:15:54ID: 25618723

    >> I need to decrypt that password value but because the existing code uses const the value never changes.  

    Which const are you referring to ?
    Which value are you referring to ?

     

    by: czlongPosted on 2009-10-20 at 14:51:17ID: 25619022

    Infinity08,

    I need to change bstrDBPassword in the below function:

    const _bstr_t & getDBPassword() const
          {
                return bstrDBPassword;
          }

    The existing code gets this value using this call: setDBPassword(iniFile.getDBPassword());

    I need to wrap it with: decrypt(char *pCode, const char *pKey) so that the bstrDBPassword value it gets from an ini file will decrypt.  The decrypt function works fine, it was successfully implemented in two other C++ programs that do not use const _bstr_t.  This particular one uses const _bstr_t causing me problems.  My C++ is way rusty.


    Thanks
    -CZ

     

    by: jkrPosted on 2009-10-20 at 14:53:59ID: 25619043

    Have you tried the 'const_cast()'? Seems to be the least intrusive way to me...

     

    by: Infinity08Posted on 2009-10-20 at 15:01:36ID: 25619110

    I still don't understand the problem.

    iniFile.getDBPassword() returns a reference to const _bstr_t. You can do with that reference whatever you want (everything except modify the _bstr_t it's referring to) ... If you need a modifiable version of it, just copy it like evilrix suggested :

            _bstr_t copy = iniFile.getDBPassword();

    and you can use the copy for whatever purpose you need it.

    How does the decrypt function fit in all this ? How does the setDBPassword function fit in all this ? Could you show us in code what you're trying to do, but doesn't work ?


    Btw, A const_cast is really a last resort solution, as it can cause more problems than it solves. I'm pretty sure there's a better way of doing this, but we'll need a bit more information for that.

     

    by: czlongPosted on 2009-10-20 at 19:16:14ID: 31643588

    evilrix and Infinity08,

    Thanks for your set of eyes and help.  After much frustration and trying both of your solutions, twice, I concluded that I must have a config problem.  My final implementation worked after correcting a dumb IDE oversight. As they say the problem was between the seat and the keyboard!

    setDBPassword(_bstr_t(decrypt(cstrParameterValue.GetBuffer(), szKey)));

    Thanks again,
    -CZ

     

    by: jkrPosted on 2009-10-21 at 06:40:59ID: 25623800

    ?

    20120131-EE-VQP-002

    3 Ways to Join

    30-Day Free Trial

    The Experts

    98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

    He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

    The Experts

    97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

    The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

    Testimonials

    "...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

    Testimonials

    "I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

    Testimonials

    "WOW! You guys have great, active, and knowledgeable people on here." moore50

    Business Clients

    Business Clients

    In the Press

    "If you’ve got a question... Experts Exchange can supply an answer.”

    In the Press

    "...an invaluable aid for both IT professionals and those who require tech support."

    In the Press

    "where IT professionals provide quick answers on just about any topic"

    Business Account Plans

    Loading Advertisement...