How to tackle a debug assertion failure?

[juhigarg]

My application during run causes a debug assertion failed with an expression _BLOCK-TYPE_IS_VALID(pHead->nBlockUse) in the file dbgheap.c (line 1017).

I understand that the problem is related to some kind of memory allocation and nothing much beyond this. I am writing and reading structs to/from files created in the program. The application reads from the created file but then gives the aforementioned error message.

First in the class Change_setting (derived from CDialog) I have written a file by the name "Group". For writting the file I am using a structure type.

Then in another class (of the same project)CLPDATADlg(again derived from CDialog) I try to read the file with the same structure. But after reading the file it gives the above error:

Below is the code for writting and reading files.

void Change_Setting::OnUpdateConfig()
{
struct Configuration
{
int portAdd;
CString TimerClk;

};
struct Configuration Config1;
CString str4;
fstream file("GROUP", ios:ut|ios::in);
if (!file){
MessageBox("Cannot Open
File","Error",MB_OK);
}

m_BaseAdd.GetWindowText(str4);
char *end;
Config1.portAdd = strtol(str4,&end,16);
Config1.TimerClk = strin7;
file.write((char*)&Config1,sizeof(Config1));
file.close();
}

void CLPDATADlg::RUN()
{
struct Configuration1
{
int portAdd;
CString TimerClk;

};
struct Configuration1 Config2;
char str2[25],strin10[25];
CString strg2,strg4,strg6,strg8;
fstream in("GROUP", ios::in|ios::binary);
if (!in){
MessageBox("Cannot Open
File","Error",MB_OK);
return;
}
in.read((char*)&Config2,sizeof(Config2));
portA = Config2.portAdd;
in.close();
}

Please help me.....I am very badly stuck.

Regards,

Juhi

[maes]

Sorry don't know the anwser to your problem. But I also had some asertoin failures. but I lost them with changing my code. My question is: What are assertion failures?

[Salem]

> in the file dbgheap.c (line 1017).
This is going to be responsible for dynamic memory allocation (via new or malloc).

Basically, between your previous call to new/malloc (which was successful), and this call (which wasn't), your code managed to corrupt the heap in some way - probably by overrunning the end of a previously allocated block.

You need to check your use of any dynamic memory, to make sure you're not overrunning the ends.

Other possibilities
- using memory after you've done delete/free on it
- using memory before you've called new/malloc