Q58956: You Cannot Decompile .EXE or .OBJ Files Back to BASIC Source

Article: Q58956
Product(s): See article
Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S890926-125 B_BasicCom | mspl13_basic
Last Modified: 26-FEB-1990

Microsoft does not currently offer any product capable of
"decompiling" an object (.OBJ) or executable (.EXE) file back to the
original source code (.BAS). The following are several reasons for
this:

1. No decompiler could exactly reproduce the original source code.

   When a program is compiled to an object and linked to produce an
   executable, most of the "names" used in the original program are
   converted to addresses. This loss of names means that a decompiler
   would have to create unique names for all the variables,
   procedures, and labels, and these names would not be meaningful in
   the context of the program.

   Obviously, source language syntax no longer exists in the compiled
   object file or executable. It would be very difficult for a
   decompiler to interpret the series of machine language instructions
   that exist in an object or executable file and decide what the
   original source language instruction was.

2. If such a decompiler did exist and was available, anyone could use
   it to decompile any executable program produced in the language the
   decompiler was designed for.

   For instance, if a Microsoft BASIC decompiler existed, anyone with
   that decompiler could use it on an executable that you had
   produced and from that executable obtain a copy of your source
   code. The source code to any program you wrote in Microsoft BASIC
   would be available to anyone with the decompiler. Few developers of
   commercial software would want to use a language product that could
   be deciphered, thus allowing others to obtain their source code.

This information applies to Microsoft QuickBASIC Versions 1.00, 1.01,
1.02, 2.00, 2.01, 3.00, 4.00, 4.00b, 4.50 for MS-DOS, to Microsoft
BASIC Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2, and to
Microsoft BASIC Professional Development System (PDS) Version 7.00 for
MS-DOS and MS OS/2.

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.