Access Violation

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Hi guys,

Am trying to send a message to list box window but i got "Access Violation Error" at the location highlighted below.

MIDL

int cstrPacketHeader= packetHeader->len;

sprintf_s(Buffer, "Lenght of Packet %d", packetHeader->len);

::SendDlgItemMessageA(Ping->m_hWnd, IDC_LIST_NIC, LB_ADDSTRING, 0, (LPARAM) Buffer);

Any solution provided will be appreciated.

Thanks

Posted 17-Oct-10 1:06am

Adeji

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2 solutions

Solution 1

Check the size of "Buffer" - is there enough room?
Shouldn't you be providing the buffer size in your sprintf_s call?
MSDN sprintf_s[^]

Posted 17-Oct-10 1:20am

OriginalGriff

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Sandeep Mewara 17-Oct-10 8:05am

Comment from OP:
Thanks for your response.

Yes, i provided the buffer size to be "char Buffer[500];" but still it doesn't work.

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Nish Nishant · Accepted Answer · 2010-10-17T02:05:00

Solution 3

Make sure packetHeader and Ping are both valid pointers.

Posted 17-Oct-10 2:05am

Nish Nishant

Comments

Adeji 17-Oct-10 8:59am

Thanks Nishant.

Have declared the Ping pointer but stepping through the codes using debugging, there in no value in Ping pointer and am not sure where it goes wrong or what else need to be declare.

Nish Nishant 17-Oct-10 9:00am

Okay, so that's what's causing the access violation.

Careful debugging should tell you how you are corrupting the pointer (it could also be due to a heap corruption elsewhere in the program).

Adeji 17-Oct-10 9:15am

Am not sure where its going wrong.
but just to be sure that am doing the right thing, i guess all i have to do to make use of "SendDlgItemMessage" is to
declare it - CWinCapTestDlg *Ping; and use it
::SendDlgItemMessage(Ping->m_hWnd, IDC_LIST_NIC, LB_ADDSTRING, 0, (LPARAM) Buffer);

is there any other thing i have to add?

Thanks.

Nish Nishant 17-Oct-10 9:17am

Well when you just declare a pointer variable, it's usually pointing to some random location (in release mode). You need to initialize it.

Adeji 17-Oct-10 9:23am

This may sound stupid, but pardon me for that.

How/where do i initialize it?

Adeji 17-Oct-10 9:51am

Thanks Nishant, i got working.
have able to figure out what you meant by initializing it.

Thanks