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MFC throws exceptions derived from the CException class which contain additional information and provide a function to show a message.
So you may add this block of code on front of your CATCH_ALL block:
CATCH(CException, pEx)
{
pEx->ReportError();
pEx->Delete();
}
The operation that might fail in your code is CString::SetAt (when the position is beyond the end of the string). This will throw an exception in release builds and assert with debug builds. Because you are not getting an assertion with a debug build, the only reason for an exception in release builds can be a different (shorter) PSW.ia string. If this is not the case the exception source is probably somewhere else.
To avoid such out of range acesses you should check the length or use a function that handles them like CString::Left.
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How about pEX->GetErrorMessage.....
I think ReportError is just a message box with out any information ?
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I must confess that I have not tested if the reporting contains the error message but assumed that it would do so.
But you can of course use GetErrorMessage with your own reporting.
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it was the SetAt Truthfully I never called the constructer so CString tempstr(&PSW.ia,16);
Thanks
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Thanks for your help answering my past queries.
If I have an array of strings:-
char*sss[10];
sss[0]="cow";
sss[1]="eland";
sss[2]="kudu";
....etc....
please how in a function can I display these strings and ask the user to choose one of these strings and get the function to return the index number of the chosen string?
I could write a function from scratch; but is there such a standard library function already?
modified 26-Jul-16 17:26pm.
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Anthony Appleyard wrote: is there such a standard library function
No, you will need to write your own.
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Hi
I am getting an Error First Chance Exception at xxxxx (ntdll.dll) access violation reading location 0xFFFFFFFFFFFFFFFF (running under the Visual Studio Debugger)
This happens after I create a CDialog with a richedit from MAINFRAME
I don't have any exception handling in my program
When I look at the stack call its some where in NTDLL tracing back to Kernel32
Could someone at the very least point me to a good place for Exception handling for beginners in MFC
Thanks
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This might not be the expected answer:
With most types of exceptions the best handling is avoiding that they occur.
This applies especially to the access violation exception. Even when catching it by code, the only reasonable "handling" is terminating the application immediately.
In your actual case you should use the debugger stepping back in the code to find out what let the exception occur. It is probably one of your objects that hasn't been initialised or set to an error state (e.g. a pointer containing the value -1) and the exception is thrown when it is used the first time (inside the kernel / ntddl in your case).
A general hint to reduce debugging time searching for the source of such exceptions is checking the success state of every function that provides one (usually the return value). The simplest way to do this is using assertions in debug build. With MFC you can use the ASSERT (MFC)[^] and VERIFY[^] macros.
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Actually that was the answer I was hoping for
I'll back track and look
At what happened right before
Thanks
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First Chance Exceptions can be benign under the debugger. Did the application crash at that point? If so, you should look at the stack trace to see what was the last line of code in your application.
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It's some time after I create a CDialog with rich edit and it is displayed a few minutes after that the exception occurs
I'll back tack and look at my code
Thanks
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I am returning to caller of SendMessage something on the stack the stack may have gotten deleted before the SendMessage completed I moved the return value to the class object
So I'll see
Thanks
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If you are returning a value then it should be OK. But if it's a pointer to a stack variable then you are probably right.
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ForNow wrote:
This happens after I create a CDialog with a richedit...
Have you remembered to call AfxInitRichEdit2() to load the richedit library?
Another option would be to temporarily add the DS_NOFAILCREATE style to the dialog. That way it'll go ahead and create/display the dialog even if there is a problem with one or more controls. When you see what control is missing, you know where to focus your efforts.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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I was doing sockets if my connect was good I issued A AfxMessageBox indicating success apparently that caused the problem I didn't use CWnd::MessageBox
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That reminds me of a guy in college who was having trouble with his program crashing. He solved the problem by adding a few calls to printf(). I just sat there with a  look in my eyes.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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 I've seen the same in assembler, "but when I put some NOP's here, it works fine!" Ugh!
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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jeron1 wrote: "but when I put some NOP's here, it works fine!"
In some cases, that can actually be the solution. 
For example, the PC/AT was too fast for some older PC peripherals, and would cause the peripherals to crash when sending back-to-back OUT commands to the peripheral. The solution was to add a NOP between the OUTs, which slowed the operation by just the right amount.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Ok, ok you got me there  . We've recently run into this, where the propagation delay of HC logic was too slow for the MCU we were using, and yes we threw in some delay. In this instance though, it was old Motorola HC11, and there was a floating input and the input read would be different depending on, apparently, the instructions that were being executed just before the read.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment
"Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst
"I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
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Hi
I have a modeless dialog box in Which I create a Rich Edit
After the Create I try to acess the Window Handle via GetSafeHwnd
Sometimes I get an exception
HWND dlgwnd;
main_app->progdbg->Create(IDD_PROGDBG,AfxGetMainWnd());
dlgwnd = main_app->progdbg->GetSafeHwnd();
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Well, Create method might fail. You are not checking its return value (it is worth noting that Create, on success, returns the handle you are searching for).
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Ok
Thanks rebuild see what happens
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ForNow wrote: Sometimes I get an exception
And exactly this exception look like?
And did you try to debug your code to be sure all the parts of your expressions are correct?
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Generate Unique Ids
FormStrings(unsigned int id, string bigText)
{
for(int x = 0; x< k; ++x)
unsigned int id uid = generateUniqueId(..);
ForwardString(uid, stringx)
}
FormStrings() method receives id which starts from 1 and increments ahead as FormStrings() method is called.
FormStrings() method further split the bigText received into smaller strings and passes to other methods.
Requirement is to generate a unique 32 bit id for the new strings created. I should also take care of how many uids are getting created from id, so that if later anyone calls delete id, all the sub-uids string should get deleted.
For example:
FormStrings(1, "Hi, I want to learn cpp.")
string1 = Hi,
String2 = I want to
String3 = learn cpp.
Here id 1 has 3 substrings. I need to create 3 uids.
Next time when FormStrings() method is called, it will come with an id 2, then 3 and so on.
I thought of creating id using 32 bits as
16 bits for id - 65535 ids
8 bits for storing number of strings formed.
but when I ran the actual program, I found out that 65535 is a small number to store id, it could be a very big number(20 bits will also not work), even number of strings formed from bigText is not fixed. I am open to create new variables, structs etc
Any suggestions are welcome.
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You could use each half of the 32 bit value such that the most significant half is the first digit (1, 2 etc.), and the second half is the string sequence number. So your id is generated by something like:
FormStrings(unsigned int id, string bigText)
{
unsigned int uid = id << 16;
for(int x = 0; x< k; ++x)
{
uid += 1;
ForwardString(uid, stringx)
}
}
This should provide enough unique values for most purposes.
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