Frequently Asked Questions

• C FAQ from comp.lang.c
• C++ FAQ from comp.lang.c++
• C-C++ FAQ from alt.comp.lang.learn.c-c++
• FAQs for other newsgroups
• Can I get it on CD?
• Where's the debugger?
• What's the version of the compiler?
• Can I download the documentation in one zip file?
• Does the WDOSX (Wuschel's DOS eXtender) work with DMC?
• Is the Zed editor still available?
• Will the compiler run under DOS?
• How do I clear the screen?
• How do I work with old CodeView?
• I need an import library for a Windows system DLL
• COFF2OMF converts .lib files to empty files?
• How do I report a bug?
• I need winfax.h or some other new Win SDK header file
• How do I use DirectX with DMC?
• How do I use wxWindows with Digital Mars?

• Compiling

  • What is the sc command?
  • Where is the header file <iostream>?
  • Redefined type errors when including the socket header files
  • When I run the compiler, it just flashes on the screen and disappears?
  • I am getting an incomprehensible error message when compiling.
  • The compiler gives me an error when accessing a base class?

• Linking

  • I'm getting 'Symbol Undefined' messages while linking
  • I'm getting 'Previous Definition Different' messages while linking
  • I'm getting 'No Start Address' messages while linking
  • I get 'Symbol Undefined _WinMain@16'?

• IDDE

  • Where's the IDDE?
  • How do I specify other compiler flags to the IDDE?
  • I'm getting a message about SCT3D32.DLL not installed
  • ClassExpress crashes reading resources created by VC++
  • IDDE sometimes can't find files, shows paths wrong?
  • Resource Editor crashes under Windows ME?
  • Why can't I create a workspace in the IDDE?
  • The IDDE doesn't seem to work with spaces in filenames

• DOSX

  • Is DOSX still available?
  • How do I access video ram in DOSX?
  • How do I call a real mode interrupt not implemented by DOSX?
  • How do I pass a buffer to a real mode interrupt?
  • NASM built .obj files crash with DOSX?

• Windows

  • How do I stop the console window from appearing?
  • A strange extra line is displayed under the menu bar?

CD now available! It's very reasonably priced at 5 plus S&H.

The CD version includes the DMC++ debugger. Alternatively, you can use any debugger that works with the Microsoft CodeView format or linker .MAP format. These include the:
• Symantec debuggers
• Zortech debuggers
• Microsoft debuggers (Codeview, symdeb, windbg, VC++ debugger). Instructions for windbg.
• Rational Systems debuggers
• Multiscope debuggers
Remember to compile with the -g option (generate symbolic debug info) and link with /co/ma.

The CD version includes the DMC++ Integrated Developing and Debugging Environment (IDDE). Alternatively, the Microemacs editor, included in the free download version, is a fully capable and powerful text editor.

The version number of the package is given by the filename starting with 'v' in the \dm directory. Individual programs in \dm\bin may have different version numbers. The version of the compiler itself can be found by typing:

\dm\bin\scppn

at the command prompt.

This happens when the program is a console program. Console programs are meant to be run from the command prompt. Most of the non-IDDE Digital Mars programs are console programs. A command prompt window can be created on XP by clicking on [Start][Command Prompt].

The compiler gives me an error when accessing a base class?

template <class T> struct Base
{
      int m_member;
};

template <class T> struct Derived : public Base<T>
{
      Derived() : m_member(0)
      {
      }
};

All the documentation comes on the CD as html files, as well as the Microsoft API documentation in Windows Help format.

DOSX is now re-released as X32 for the Digital Mars compilers, and is now available again! Download the patch for X32, and X32 itself. If you need the old Symantec or Zortech dos extender version, and you have an original licensed copy of the Zortech or Symantec compilers, copy these files:

lib\sdx.lod
lib\cx.obj
src\dos32\cx.asm
src\dos32\lib\x386.lib

into the same directories and then you can develop for DOSX again.

I don't know, but I don't see why not. Check it out at www.wuschel.demon.co.uk.

It appears to be here.

No. Although the compiler will build 16 bit DOS programs, the compiler itself will only run under Win32. The dos extended versions of the tool executables are no longer included. Symantec does offer a freely downloadable set of compilers that run under DOS here. (This link appears to be broken.)

To give 'other' flags (newer ones not on the property pages) such as -Ab, use the 'defines' edit box and give the flags there. In such a case, you must explicitely use -D for your defines. If you are only defining, then -D is not required.

e.g. If you want to define 'NDEBUG' only, specify only 'NDEBUG'. If in addition, you want to specify -Ab, you must write:

-Ab -DNDEBUG

There are some name collisions by default when including the socket header files. It reports about 5 redefined variable types, fd_set being among them. fd_set can also be found in types.h and unistd.h.

The solution is to #define _WIN32_WINNT 0x0400 in order to force windows.h to include winsock2.h, not winsock.h.

This can happen when creating an application using the AppExpress feature of ProjectExpress [Project->New] in the IDDE. Clicking "use AppExpress" followed by "finish", the message in a window titled CTL3DV2 appears:

"This application uses SCT3D32.DLL, which has not been correctly
installed."

This message is generated by SCT3D32.DLL itself (a Microsoft supplied DLL), and is produced when it is not residing in the system directory. SCT3D32.DLL is in the \dm\bin directory. Copy it to your windows system directory (which on NT is \winnt40\system32), and rename the one in \dm\bin to SCT3D32.DLL.OLD.

This is the only known DLL with this problem.

The problem:

Compiling a test program like this,

dmc -ms -0 -g -L/co/ma foo.c

and proceeding to load CodeView in "real" DOS produces the message:

CV0104 Warning:  CodeView information for 'D:\FOO.EXE' is
newer than this version of CodeView

The version of codeview is 4.01 as supplied in the MASM 6.11 package, dated from 1992. Using /cvversion:4 to the linker produces the same result, as well as using compiler option -g4. Using masm to assemble an example program and linking using Microsoft Link does work with codeview. Linking the same .obj file with optlink/cvversion:4 produces the same failure.

The solution:

Optlink runs cvpack when generating cv4 info. This seems to be the cause of the trouble: cv only gives the "info is newer than this version of codeview" error when cvpack is executed without any options. When optlink is given the /nocvpack option, then run cvpack manually with the minimal option, the debugger (cv) then reports with symbolic names. For example:

dmc -ms -0 -g -L/co/l/i/nocv foo.exe
cvpack /minimal foo.exe

and cv will work.

(Thanks to Jack Jay for tracking this down.)

Consider the following program test.c:

#include <windows.h>

void main()
{
     gethostbyname(0);
}

The function gethostbyname() is declared in \dm\include\win32\winsock.h, and is exported from the Windows system dLL wsock32.dll. Compiling and linking test.c produces:

E:>dmc test
link test,,,user32+kernel32/noi;
OPTLINK (R) for Win32  Release 7.50B1
Copyright (C) Digital Mars 1989 - 2001  All Rights Reserved

test.obj(test)
 Error 42: Symbol Undefined _gethostbyname@4

--- errorlevel 1

E:>

If implib is run over wsock32.dll to create wsock32.lib, it still doesn't link because the name in wsock32.dll is gethostbyname, not _gethostbyname@4. The solution is to create a module definition file wsock32.def with the contents:

LIBRARY wsock32
EXETYPE NT
SUBSYSTEM WINDOWS
EXPORTS
    _gethostbyname@4  = gethostbyname

This establishes a translation from one name to the other. Add each of the exports needed. Then run implib over it with:

implib wsock32.lib wsock32.def

and link with:

dmc test.obj wsock32.lib

and it should then link successfully.

Some parts of the IDDE cannot deal with paths and filenames that have embedded spaces in them, for example if some of the source files are in: \program files\dev\dm (note embedded space between "program" and "files"). The solution is to (1) use paths that don't embed spaces or (2) use the subst command, i.e. subst z: \program files\dev and then refer to the files as being off of z: in the IDDE.

(Thanks to Chris Widdows and Jan Knepper for tracking this down.)

Windows SDK updates can be downloaded from sdkupdate which includes winfax.h.

When starting RS32 under WinME, it crashes with "Abnormal program termination", and then a page fault in SFC30.DLL. The fix is to install Microsoft's update for Microsoft Explorer MSIE5.5 SP2. This apparently updates some broken system DLLs.

(Thanks to Laurentiu Pancescu for tracking this down.)

You can get .lib files from MS DIRECTX SDK and convert them to OMF format with coff2omf. Then use the .h files from the same SDK. If using only a limited set of DirectX functions, it is possible to build a .lib from .DLL using the implib utility.

(Thanks to Nic Tiger.)

The menu items Environment->Workspace->New or Environment->Workspace->Clone are always grayed in the installation. The limit is 5 workspaces, and as delivered on the CD there are already 5. To create a new workspace, delete one of the existing ones first.

(Thanks to Frank Albe.)

The IDDE cannot handle spaces, + signs, or ~ characters in filenames or path names. It cannot be installed in a directory with such characters in it, for example, it cannot be installed under \Program Files\.

• Add the following switch:

  -I\dm\stlport\stlport
  

  when compiling.
• Add \dm\stlport\stlport to the INCLUDE environment variable search path before \dm\include.
• Modify the INCLUDE entry in \dm\bin\sc.ini to be:

  INCLUDE="%@P%\..\stlport\stlport";"%@P%\..\include";"%@P%\..\mfc\include";%INCLUDE%
  

link /NOI /DE /PACKF /XN /NT /ENTRY:WinMainCRTStartup /BAS:4194304 /A:512
@tst.LNK
Error: c:\dm\lib\SNN.lib(winstart)  : Symbol Undefined _WinMain@16
Errors: 1  Warnings: 0
Build failed

If using a module definition (.def) file, these lines should appear in it:

EXETYPE          NT
SUBSYSTEM        CONSOLE

1. Redirect the output of the makefile to a .bat file:

   make -ffoo.mak >cc.bat
   

2. Edit cc.bat so it is just compiling the source file that fails.
3. Rename the source file that fails to test.cpp, and edit cc.bat so it is compiling test.cpp.
4. Remove any precompiled header switches from cc.bat.
5. Ruthlessly hack off chunks of test.cpp until the smallest source file remains that still shows the error.
6. Many projects #include a complicated, confusing mass header files from multiple locations. These header files will also be commonly filled with macros and #if's, making it really hard to be sure what is going on in them. Add the -e and -l switches to cc.bat, which will produce a file called test.lst. This file will have all the #include files included, and all macros will be expanded, and all false conditional code will be removed. Rename test.lst to test.cpp, and continue hacking and slashing off all the code that does not contribute to the error message.

EXETYPE       NT
SUBSYSTEM     WINDOWS

EXETYPE NT
SUBSYSTEM WINDOWS,4.0