Re: [Mingw-users] Modifying LPTSTR strings causing a crash

[Keith M. <kei...@us...>]

On 27/02/12 04:21, Wayne Porter wrote:
> // Check for an ending slash and add one if it is missing.
> 
> lpEnd = lpSubKey + lstrlen(lpSubKey);

How is the memory referenced by lpSubKey originally declared?  Is it
guaranteed to point to a writeable data section?  Is the buffer at that
address guaranteed to have free space at the end, to accommodate the
extra '\\' you're trying to append.

> if (*(lpEnd - 1) != TEXT('\\'))
> {
>     *lpEnd =  TEXT('\\');  // This line crashes the app

I'm guessing, (because you haven't provided us with enough diagnostic
information -- how does it crash?  what is the error message? -- for me
to do otherwise), that you are trying to modify data in a read-only
section; (hint:

  char *lpKey = "string constant";

and lpSubKey pointing to a sub-string of lpKey, makes *lpSubKey a
read-only reference).

>     lpEnd++;
>     *lpEnd =  TEXT('\0'); // This one crashes too

Likely for the same reason.

> }
> 
> 
> I'm not sure how to start debugging, but I also don't understand why
> this is failing.

Without seeing the info you failed to provide, I don't either.

-- 
Regards,
Keith.