[Mingw-users] Modifying LPTSTR strings causing a crash

Trying to delete registry keys and having a problem with the code I have
been working with. The address on MSDN below has an example and I've
modified it to work except for one part.

http://msdn.microsoft.com/en-us/library/windows/desktop/ms724235(v=vs.85).aspx


// Check for an ending slash and add one if it is missing.

lpEnd = lpSubKey + lstrlen(lpSubKey);

if (*(lpEnd - 1) != TEXT('\\'))
{
    *lpEnd =  TEXT('\\');  // This line crashes the app
    lpEnd++;
    *lpEnd =  TEXT('\0'); // This one crashes too
}


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