Solved

Problem with RegQueryValueEx

Posted on 1997-06-08
2
741 Views
Last Modified: 2013-11-20
I'm having a problem with the RegQueryValueEx function - it's returning error code 87 (Invalid Parameter), and it's due to the 5th parameter.  I know this, because it returns ERROR_SUCCESS if I make this parameter NULL.

      CString sPwd;
      HKEY      phk;
      char      sPwdReg[10];
      DWORD      dwType;
      DWORD      dwcbData;

//#ifdef WIN32_EXTRA_LEAN
//      this_statement_will_generate_compile_error;
//#endif
      if (::RegOpenKeyEx(HKEY_CURRENT_USER, "Software\\a\\b",
                  0, KEY_ALL_ACCESS, &phk) != ERROR_SUCCESS)
            return;
      AfxMessageBox("OpenKey worked");

      long lRet = ::RegQueryValueEx(phk, (LPTSTR) "Password", NULL, NULL,
                  (LPBYTE) sPwdReg, &dwcbData);

      AfxMessageBox("QueryValue worked");

      CString msg;
      msg.Format("lRet = %ld", lRet);
      AfxMessageBox(msg);

The "Password" registry value is a string, by the way.  Does anybody know what I'm doing wrong here?  I've looked through all the examples in the Visual C++ documentation, and found no clues.  I've seen this argument typecast to LPCTSTR or LPTSTR, but this won't compile.  I've also tried using a char* argument, and allocating memory to it with malloc, but this shouldn't make a difference, and it didn't.

A possibly related problem is that in my Project Settings/C/C++ Tab/Preprocessor Category, I have undefined WIN32_EXTRA_LEAN in order for the compiler to include "winreg.h", which is needed for the registry API.  However, if I uncomment the #ifdef WIN32_EXTRA_LEAN directive, I find that WIN32_EXTRA_LEAN *is* defined.  I cannot figure this out - I'm working around it by just explicitly including "winreg.h".
0
Comment
Question by:nbranitsky
2 Comments
 
LVL 23

Accepted Solution

by:
chensu earned 100 total points
ID: 1302032
You should initialize dwcbData to the size of the buffer in bytes before passing it to ::RegQueryValueEx().

DWORD dwcbData = sizeof(sPwdReg);

0
 

Author Comment

by:nbranitsky
ID: 1302033
Thanks.  That should teach me to read the documentation more closely!
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Pressing cancel button with C# UI Automation 3 51
java ^ examples 8 62
sumHeights2  challenge 7 87
wordappend challenge 8 143
Here is how to use MFC's automatic Radio Button handling in your dialog boxes and forms.  Beginner programmers usually start with a OnClick handler for each radio button and that's just not the right way to go.  MFC has a very cool system for handli…
Introduction: Finishing the grid – keyboard support for arrow keys to manoeuvre, entering the numbers.  The PreTranslateMessage function is to be used to intercept and respond to keyboard events. Continuing from the fourth article about sudoku. …
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Need to grow your business through quality cloud solutions? With everything required to build a cloud platform and solution, you may feel like the distance between you and the cloud is quite long. Help is here. Spend some time learning about the Con…

932 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

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now