Unhandled Exception:Access Violation Error

Question

0.00/5 (No votes)

See more:

Hello Everyone,

Am working creating MFC DLL & am getting an error:Unhandled exception at 0x00000000 in Key_Testing.exe: 0xC0000005: Access violation.

The DLL Code is like this:

C#

//Demo.h
char*	GetDiskSerialNumber (char g_DiskLetter);

//Demo.cpp
char* DLLclass::GetDiskSerialNumber(char g_DiskLetter)
{
	CHAR SN[64];
	memset(SN,0,sizeof(SN));
		
	if(GetSerialNumber(SN,g_DiskLetter)){   // Error in this Line..
		return (char*)SN;
	}
}

This DLL am using in an application..
void CKey_TestingDlg::OnBnClickedgetserial()
{
	// TODO: Add your control notification handler code here
	DLLclass Dllobj;
	char ltr='h';
	char* ser=Dllobj.GetDiskSerialNumber(ltr);
}

Please,, Could anyone suggest where i gone wrong.. Any help will be appriciated..

Thank you.

Posted 24-Jan-12 18:52pm

Guru_C++

Updated 24-Jan-12 18:55pm

Prasad_Kulkarni

v2

Add a Solution

Comments

Lakamraju Raghuram 25-Jan-12 1:20am

Can you give info about GetSerialNumber(...) method you are using

Guru_C++ 25-Jan-12 2:05am

Thanks for your help :) Function Declaration for GetSerialNumber is like this:
typedef BOOL (WINAPI *GetSerialNumberDLL)(CHAR* , CHAR );

Mohibur Rashid 25-Jan-12 2:31am

boolian pointer? are you sure?

Guru_C++ 25-Jan-12 2:17am

I changed my code as per as ur suggestion.. Still a getting same error..:(

Guru_C++ 25-Jan-12 3:08am

Yes John.. Its boolian pointer..

Stefan_Lang 25-Jan-12 4:17am

Erm, no...

If my understanding of function pointers serves me well, the type you defined is a pointer to a function that returns BOOL, not a function that returns pointer to BOOL as John implied.

But I might be wrong, I never use function pointers myself ;)

P.S.: If my understanding is correct, then shouldn't you invoke the function like this:
if ((*GetSerialNumber)(...))
? (just guessing, I might be wrong)

2 solutions

Solution 2

GetDiskSerialNumber is returning a pointer to a local array. This is not valid. Local variables die when the function exits as they reside on the stack.

Posted 24-Jan-12 23:50pm

BrainlessLabs.com

Comments

Guru_C++ 25-Jan-12 7:54am

Yes ur correct.. And, Also am derefrencing a null pointer. But, am not getting how to modify the code..

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

«_Superman_» · Accepted Answer · 2012-01-24T19:22:00

What is the code inside GetSerialNumber?
There is probably some error there.

Also, you're declaring a local array and returning its address, which will no longer be valid when the function returns.

Instead change it as follows -

void DLLclass::GetDiskSerialNumber(char g_DiskLetter, char* SN)
{
	GetSerialNumber(SN, g_DiskLetter);
}
 
void CKey_TestingDlg::OnBnClickedgetserial()
{
	// TODO: Add your control notification handler code here
	DLLclass Dllobj;
	char ltr='h';

	CHAR SN[64];
	memset(SN,0,sizeof(SN));

	Dllobj.GetDiskSerialNumber(ltr, SN);
}