C / C++ / MFC

Re: WaitForMultipleObjects getting access violation in Worker Thread

10-May-21 4:06

ForNow wrote:
don’t think the wait should be in the main thread

If you would implement the Wait... in the main thread then you could wait forever and your main thread could be frozen forever.

BTW, how do you create/obtain the event HANDLEs that you pass in the WaitForMultipleObjects? Are they all correct?

modified 10-May-21 10:37am.

ForNow10-May-21 4:25

Re: WaitForMultipleObjects getting access violation in Worker Thread

10-May-21 4:25

I am using CreateEvent as it gives me more flexibility i.e auto reset As opposed to WSACreateEvent I then pass everything in a structure pointed to by LPVOID had to build it with no alignment (Zp1) as I was getting slack bytes among members of the structure

thanks

Victor Nijegorodov10-May-21 4:39

Re: WaitForMultipleObjects getting access violation in Worker Thread

10-May-21 4:39

Could you post some code snippets describing what you do?

ForNow10-May-21 4:51

Re: WaitForMultipleObjects getting access violation in Worker Thread

10-May-21 4:51

sure be glad to in fact I appreciate it Am at work now (I work as a z/os Mainframe assemnbler programmer ) this has given me a chance to enhance my skills its 10:50 am here EST get off of work 5:00 - 5;30 will do it then thanks for your help

Randor 11-May-21 12:30

Randor

11-May-21 12:30

ForNow wrote:
I pass all the info (HWND windows

The MFC framework does not always give you the *real* HWND to a window. As strange as this might sound, the MFC framework maintains two object maps. The 'real objects' and an internal 'temporary handle map'. MFC will sometimes give you a temporary CTempWnd instead. If you are passing the window handle of a MFC class then you need to use CWnd::GetSafeHwnd[^]. There are some rare occasions where GetSafeHwnd cannot give you the real window handle and will return NULL instead so you should probably check for that too.

Not many people are using MFC these days. You should consider moving on.

I can't think of much else that would cause WaitForMultipleObjects to throw an access violation. The only other thing I can think of... is a corrupt heap. Sounds like you are somehow passing garbage to WaitForMultipleObjects.

Best Wishes,
-David Delaune

Re: WaitForMultipleObjects getting access violation in Worker Thread

ForNow12-May-21 1:36

Re: WaitForMultipleObjects getting access violation in Worker Thread

12-May-21 1:36

Thanks I had some other problems
I got rid of the WaitForMultipleObjects and set all my notifications on one event and extracted the correct one with WSAENumnetwork that worked when you say not many people are using MFC do yo mean they coding Windows C API
I found CAsynsockets to be a pain I couldn’t pass along notification to another window
Thanks

Victor Nijegorodov12-May-21 2:00

Re: WaitForMultipleObjects getting access violation in Worker Thread

12-May-21 2:00

ForNow wrote:
when you say not many people are using MFC do yo mean they coding Windows C API
I found CAsynsockets to be a pain I couldn’t pass along notification to another window

I guess he meant they use C#.

I used CAsyncSocket class successfully since many years (until I have changed the company to work for). I never had any problems with this class to work with both IPv4 and IPv6 sockets in IPC with multiple sockets through intranet and internet.

ForNow12-May-21 2:30

Re: WaitForMultipleObjects getting access violation in Worker Thread

12-May-21 2:30

C/C++ has pointers which gives me flexibility same with native sockets “WSA” when I tried moving my derived CAsyncSocket object pointer notification from a main window to a dialog I ran into problems. No where in the documentation does it say there has to be HWND associated with your CasyncSockets but you have to
I was using CWinThread for notification it has a message pump but doesn’t have a HWND although there is hWnd member ( I think main windows ) member thanks

Victor Nijegorodov12-May-21 2:37

Re: WaitForMultipleObjects getting access violation in Worker Thread

12-May-21 2:37

It is very hard to understand what you mean, much more harder is to understand what, how, and what for you have implemented in your project. The reason - you avoid to show your code/pseudocode snippets.
Sorry... Unsure | :~

ForNow12-May-21 2:47

12-May-21 2:47

I’ll do that tonite ( it’s 8:45 est by me ) wanted to fix up my code

Thanks

Ajay Kumar May20214-May-21 20:49

Ajay Kumar May2021

4-May-21 20:49

Question: 
Replace all the vowels of the given input string with a single digit number.
Input: 
String of length L and all lower-case letters.
Output: 
Input String replaced with the digit.
Program explanation: 
Replace all the vowels in the given input string with a single digit number you get after all the below 
steps.
Step 1: Get the index of the vowel in the given input.
Step 2: Multiply the index with 100.
Step 3: Sum all the prime numbers between 1 and the resulting number from last step.
Step 4: Add the digits of the number you get from the last step until you get a single digit.
Step 5: Now, Replace the vowel with the digit from the last step.

Input:
hello
Output:
h7ll9
Explanation:
Step 1: First vowel found at index 1.
Step 2: 1 * 100 = 100
Step 3: Sum of prime numbers between 1 and 100 is 1060
Step 4: Sum of each digit until we get single digit:
= 1 + 0 + 6 + 0
= 7
Step 5: Replace e with 7
Output now: h7llo
Step 1: Next vowel found at index 4.
Step 2: 4 * 100 = 400
Step 3: Sum of prime numbers between 1 and 400 is 13887
Step 4: Sum of each digit until we get single digit:
= 1 + 3 + 8 + 8 + 7
= 27
= 2 + 7
= 9
Step 5: Replace o with 9
Final output: h7ll9
Example 2:
Input : replace this
Output. : r7pl9c1 th5s

Re: C,

Richard MacCutchan4-May-21 21:23

C2065 'IUrlHistoryStg2Ptr': undeclared identifier

4-May-21 21:23

Sorry, but this site does not provide code to order. This is your assignment so you are expected to do the work. If you need some guidance to get started then take a look at How to Write Code to Solve a Problem, A Beginner's Guide[^].

Re: C,

Gerry Schmitz5-May-21 8:29

Gerry Schmitz

5-May-21 8:29

Step 0: Get input.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

Saikat_EPAM28-Apr-21 22:25

Saikat_EPAM

28-Apr-21 22:25

Hello Team,

I am getting the below error while building my MFC project.

C2065 'IUrlHistoryStg2Ptr': undeclared identifier

I have included the <urlhist.h> header file and it is there under the 'External Dependencies' folder.

Could you please suggest me how I can resolve the issue.

Thanking you,
Saikat Das

Software Programmer

Re: C2065 'IUrlHistoryStg2Ptr': undeclared identifier

Richard MacCutchan28-Apr-21 23:12

Re: C2065 'IUrlHistoryStg2Ptr': undeclared identifier

28-Apr-21 23:12

I cannot find any reference to IUrlHistoryStg2Ptr in the urlhist.h file, or in the IUrlHistory (Windows) | Microsoft Docs[^] documentation either. So where did you find the reference?

CPallini29-Apr-21 0:20

CPallini

29-Apr-21 0:20

Maybe here at CodeProject: Access Internet Explorer's History in MFC[^]. Smile | :)

"In testa che avete, Signor di Ceprano?"
-- Rigoletto

Re: C2065 'IUrlHistoryStg2Ptr': undeclared identifier

Victor Nijegorodov29-Apr-21 1:51

Re: C2065 'IUrlHistoryStg2Ptr': undeclared identifier

29-Apr-21 1:51

And according to the discussion below the article Access Internet Explorer's History in MFC :

Quote:
Go to Parentinsert these in IEHistory.h
typedef IUrlHistoryStg2* IUrlHistoryStg2Ptr;
typedef IEnumSTATURL* IEnumSTATURLPtr;

Richard MacCutchan29-Apr-21 2:18

Re: How to "link" two C++ applications ?

29-Apr-21 2:18

See @Victor-Nijegorodov's message below.

Message Closed

28-Apr-21 4:41

Member 14968771

28-Apr-21 4:41

Message Closed

modified 15-May-23 19:07pm.

Richard MacCutchan28-Apr-21 5:41

Re: How to "link" two C++ applications ?

28-Apr-21 5:41

Member 14968771 wrote:
I still cannot use my "old - few years " account.

Then post a question at Bugs and Suggestions[^] and the administrators will help you.

Sean Ewington28-Apr-21 5:45

Sean Ewington

28-Apr-21 5:45

Send me an email (sean@codeproject.com) and I will help get you access to your old account.

Thanks,
Sean Ewington
CodeProject

WSARecv question

ForNow25-Apr-21 17:17

CAyncSocket::Detach Fails _AFX_SOCK_THREAD_STATE* pState-> m_hSocketWindow == NULL

25-Apr-21 17:17

The WSARecv winsock api has the ability to do overlapped i/o the second parameter is the number of WSABUFs

The sixth parameter is a overlapped structure, the 5th parameter of the overlapped is one or MORE WSAevents I would be doing a

C++

WSAWaitForMultipleEvents

with each event corresponding to a buffer when WSAevent ...n is signaled WSABUF ... n would have data I would then have to put the buffer back together think I got it right

thanks

Forgot one more thing I am doing WSAAsyncSelect to have a receive notification sent to the window when that message is sent I am assuming i/o is Imminent should I create a thread to do the

C++

WSAWaitForMultipleEvents

or since I got a notification the receive is about to happen doing it in the window under the main thread is ok

thanks

modified 25-Apr-21 23:30pm.

ForNow25-Apr-21 3:57

Re: CAyncSocket::Detach Fails _AFX_SOCK_THREAD_STATE* pState-> m_hSocketWindow == NULL

25-Apr-21 3:57

hI
I create four CAsynSocket Classes in four CwinThread classes When I first create them Socket (with notification events) bind ioctl, setsockopt. I follow the CASynSocket::Socket call to sockcore.cpp and

C++

pState-> m_hSocketWindow

has a valid Hwnd Value. The context of the creation of sockets in the CwinApp after my main CFrameWnd has been created.

I then start a conversation with the server (connect send and then receive). It is at a point that I would like to give the work over to a modeless dialog. this is where things go wrong. After getting a message
from the server I try to do a detach which goes to

C++

CAsyncSocket::AsyncSelect(long lEvent)

however at this point

C++

_AFX_SOCK_THREAD_STATE* pState-> m_hSocketWindow == NULL

is NULL

Since I was debugging this in release mode I never got the subsequent assert on this.

First off in the documentation for CAsynSocket there is no mention that i need a Hwnd to process the class when I first did the CAsynSocket::Socket call with the event notification that I wanted to be informed on
I did notice that

C++

pState-> m_hSocketWindow

had a valid window

When I first started using CAsyncSocket I know very little about TCPI/IP or OO

at this point looking at Winscok API it has much more flexability so much so it seem I dont necessary need a valid Hwnd but a kernel object such as that from CreateEvent will do
more so It seems if I want to pass notification to a different windows I just do another call to

WSAAsyncSelect

with a new HWND

Still I am wondering why

C++

pState-> m_hSocketWindow

went to NULL

Mircea Neacsu25-Apr-21 5:38

Mircea Neacsu

25-Apr-21 5:38

It's probably not fair to send you down a different path, but many years ago I had similar problems and, having some spare time, I decided to make my own set of wrappers for Windows Sockets API. Over time it has grown into a quite capable set of objects that allow you to work with sockets just like you work with C++ streams.

I've wrote a series of articles here and you can take a look see if they are of any help to you:
- Windows Sockets Streams[^]
- Windows Sockets Streams Part II - Multi-Threaded TCP Servers[^]
- Windows Sockets Streams Part III - HTTP Server[^]

Latest version of code can be downloaded from GitHub[^].

Mircea

Re: CAyncSocket::Detach Fails _AFX_SOCK_THREAD_STATE* pState-> m_hSocketWindow == NULL

ForNow25-Apr-21 5:52