Category : C Source Code
Archive   : C-ALL.ZIP
Filename : TI648.ASC

PRODUCT : Borland C++ NUMBER : 648
VERSION : 2.0
OS : PC DOS
DATE : September 11, 1991 PAGE : 1/1

TITLE : Common Causes of General Protection Faults in TDW




The following are common causes for General Protection faults
while debugging a Windows application under Turbo Debugger for
Windows (TDW.EXE):

a) ram has called a Windows API function with incorrect arguments.
For example, passing WndProc a handle which is invalid.

b) The segment part of a pointer the program is using is invalid.
In protected mode it is an index into the selector table which
has the actual segment address. If that index references a spot
in the table which it shouldn't, or goes outside the bounds of
the table, it can cause a GP.

c) The user's WndProc function uses a handle between function calls
which has not been declared static, so the value has changed.

d) The CreateWindow API function calls your WndProc function with 3
messages. If WndProc is not debugged, it can cause problems
(like a GP).