D Programming Language 2.0

Last update Fri Jan 20 13:27:27 2012


This describes the D implementation for 32 bit Windows systems. Naturally, Windows specific D features are not portable to other platforms.

Instead of the:

#include <windows.h>

of C, in D there is:

import std.c.windows.windows;

Calling Conventions

In C, the Windows API calling conventions are __stdcall. In D, it is simply:

extern (Windows)
	/* ... function declarations ... */

The Windows linkage attribute sets both the calling convention and the name mangling scheme to be compatible with Windows.

For functions that in C would be __declspec(dllimport) or __declspec(dllexport), use the export attribute:

export void func(int foo);

If no function body is given, it's imported. If a function body is given, it's exported.

Windows Executables

Windows GUI applications can be written with D. A sample such can be found in \dmd2\samples\d\winsamp.d

These are required:

  1. Instead of a main function serving as the entry point, a WinMain function is needed.
  2. WinMain must follow this form:
    import core.runtime;
    import std.c.windows.windows;
    import std.string;
    extern (Windows)
    int WinMain(HINSTANCE hInstance,
        HINSTANCE hPrevInstance,
        LPSTR lpCmdLine,
        int nCmdShow)
      int result;
      void exceptionHandler(Throwable e) {
        throw e;
      try {
        result = myWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
      catch (Throwable e) { // catch any uncaught exceptions
        MessageBoxA(null, e.toString().toStringz, "Error",
        result = 0;             // failed
      return result;
    int myWinMain(HINSTANCE hInstance,
        HINSTANCE hPrevInstance,
        LPSTR lpCmdLine,
        int nCmdShow)
      // ... insert user code here ...
      return 0;
    The myWinMain() function is where the user code goes, the rest of WinMain is boilerplate to initialize and shut down the D runtime system.
  3. A .def (Module Definition File) with at least the following two lines in it:
    Without those, Win32 will open a text console window whenever the application is run.
  4. The presence of WinMain() is recognized by the compiler causing it to emit a reference to __acrtused_dll and the phobos.lib runtime library.

Windows Programming Examples

A collection of over 140 Windows D programming code examples is available at this Github repository.

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