RegisterClassW

// USER32.dll  (Unicode / -W)
#include <windows.h>

WORD RegisterClassW(
    const WNDCLASSW* lpWndClass
);

<DllImport("USER32.dll", CharSet:=CharSet.Unicode, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function RegisterClassW(
    lpWndClass As IntPtr   ' WNDCLASSW*
) As UShort
End Function

' lpWndClass : WNDCLASSW*
Declare PtrSafe Function RegisterClassW Lib "user32" ( _
    ByVal lpWndClass As LongPtr) As Integer
' Unicode(W): 文字列は ByVal As LongPtr とし StrPtr(unicodeStr) を渡す
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

RegisterClassW = ctypes.windll.user32.RegisterClassW
RegisterClassW.restype = ctypes.c_ushort
RegisterClassW.argtypes = [
    ctypes.c_void_p,  # lpWndClass : WNDCLASSW*
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
RegisterClassW = Fiddle::Function.new(
  lib['RegisterClassW'],
  [
    Fiddle::TYPE_VOIDP,  # lpWndClass : WNDCLASSW*
  ],
  -Fiddle::TYPE_SHORT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "user32")]
extern "system" {
    fn RegisterClassW(
        lpWndClass: *const WNDCLASSW  // WNDCLASSW*
    ) -> u16;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern ushort RegisterClassW(IntPtr lpWndClass);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_RegisterClassW' -Namespace Win32 -PassThru
# $api::RegisterClassW(lpWndClass)

#uselib "USER32.dll"
#func global RegisterClassW "RegisterClassW" wptr
; RegisterClassW varptr(lpWndClass)   ; 戻り値は stat
; lpWndClass : WNDCLASSW* -> "wptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "USER32.dll"
#cfunc global RegisterClassW "RegisterClassW" var
; res = RegisterClassW(lpWndClass)
; lpWndClass : WNDCLASSW* -> "var"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; WORD RegisterClassW(WNDCLASSW* lpWndClass)
#uselib "USER32.dll"
#cfunc global RegisterClassW "RegisterClassW" var
; res = RegisterClassW(lpWndClass)
; lpWndClass : WNDCLASSW* -> "var"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procRegisterClassW = user32.NewProc("RegisterClassW")
)

// lpWndClass (WNDCLASSW*)
r1, _, err := procRegisterClassW.Call(
	uintptr(lpWndClass),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // WORD

function RegisterClassW(
  lpWndClass: Pointer   // WNDCLASSW*
): Word; stdcall;
  external 'USER32.dll' name 'RegisterClassW';

result := DllCall("USER32\RegisterClassW"
    , "Ptr", lpWndClass   ; WNDCLASSW*
    , "UShort")   ; return: WORD

●RegisterClassW(lpWndClass) = DLL("USER32.dll", "int RegisterClassW(void*)")
# 呼び出し: RegisterClassW(lpWndClass)
# lpWndClass : WNDCLASSW* -> "void*"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。