HtmlHelpW

// hhctrl.ocx  (Unicode / -W)
#include <windows.h>

HWND HtmlHelpW(
    HWND hwndCaller,   // optional
    LPCWSTR pszFile,
    DWORD uCommand,
    UINT_PTR dwData
);

<DllImport("hhctrl.ocx", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function HtmlHelpW(
    hwndCaller As IntPtr,   ' HWND optional
    <MarshalAs(UnmanagedType.LPWStr)> pszFile As String,   ' LPCWSTR
    uCommand As UInteger,   ' DWORD
    dwData As UIntPtr   ' UINT_PTR
) As IntPtr
End Function

' hwndCaller : HWND optional
' pszFile : LPCWSTR
' uCommand : DWORD
' dwData : UINT_PTR
Declare PtrSafe Function HtmlHelpW Lib "hhctrl.ocx" ( _
    ByVal hwndCaller As LongPtr, _
    ByVal pszFile As LongPtr, _
    ByVal uCommand As Long, _
    ByVal dwData As LongPtr) As LongPtr
' 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

HtmlHelpW = ctypes.windll.LoadLibrary("hhctrl.ocx").HtmlHelpW
HtmlHelpW.restype = ctypes.c_void_p
HtmlHelpW.argtypes = [
    wintypes.HANDLE,  # hwndCaller : HWND optional
    wintypes.LPCWSTR,  # pszFile : LPCWSTR
    wintypes.DWORD,  # uCommand : DWORD
    ctypes.c_size_t,  # dwData : UINT_PTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('hhctrl.ocx')
HtmlHelpW = Fiddle::Function.new(
  lib['HtmlHelpW'],
  [
    Fiddle::TYPE_VOIDP,  # hwndCaller : HWND optional
    Fiddle::TYPE_VOIDP,  # pszFile : LPCWSTR
    -Fiddle::TYPE_INT,  # uCommand : DWORD
    Fiddle::TYPE_UINTPTR_T,  # dwData : UINT_PTR
  ],
  Fiddle::TYPE_VOIDP)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "hhctrl.ocx")]
extern "system" {
    fn HtmlHelpW(
        hwndCaller: *mut core::ffi::c_void,  // HWND optional
        pszFile: *const u16,  // LPCWSTR
        uCommand: u32,  // DWORD
        dwData: usize  // UINT_PTR
    ) -> *mut core::ffi::c_void;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("hhctrl.ocx", CharSet = CharSet.Unicode)]
public static extern IntPtr HtmlHelpW(IntPtr hwndCaller, [MarshalAs(UnmanagedType.LPWStr)] string pszFile, uint uCommand, UIntPtr dwData);
"@
$api = Add-Type -MemberDefinition $sig -Name 'hhctrl.ocx_HtmlHelpW' -Namespace Win32 -PassThru
# $api::HtmlHelpW(hwndCaller, pszFile, uCommand, dwData)

#uselib "hhctrl.ocx"
#func global HtmlHelpW "HtmlHelpW" wptr, wptr, wptr, wptr
; HtmlHelpW hwndCaller, pszFile, uCommand, dwData   ; 戻り値は stat
; hwndCaller : HWND optional -> "wptr"
; pszFile : LPCWSTR -> "wptr"
; uCommand : DWORD -> "wptr"
; dwData : UINT_PTR -> "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 "hhctrl.ocx"
#cfunc global HtmlHelpW "HtmlHelpW" sptr, wstr, int, sptr
; res = HtmlHelpW(hwndCaller, pszFile, uCommand, dwData)
; hwndCaller : HWND optional -> "sptr"
; pszFile : LPCWSTR -> "wstr"
; uCommand : DWORD -> "int"
; dwData : UINT_PTR -> "sptr"

; HWND HtmlHelpW(HWND hwndCaller, LPCWSTR pszFile, DWORD uCommand, UINT_PTR dwData)
#uselib "hhctrl.ocx"
#cfunc global HtmlHelpW "HtmlHelpW" intptr, wstr, int, intptr
; res = HtmlHelpW(hwndCaller, pszFile, uCommand, dwData)
; hwndCaller : HWND optional -> "intptr"
; pszFile : LPCWSTR -> "wstr"
; uCommand : DWORD -> "int"
; dwData : UINT_PTR -> "intptr"

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

var (
	hhctrl_ocx = windows.NewLazySystemDLL("hhctrl.ocx")
	procHtmlHelpW = hhctrl_ocx.NewProc("HtmlHelpW")
)

// hwndCaller (HWND optional), pszFile (LPCWSTR), uCommand (DWORD), dwData (UINT_PTR)
r1, _, err := procHtmlHelpW.Call(
	uintptr(hwndCaller),
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszFile))),
	uintptr(uCommand),
	uintptr(dwData),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HWND

function HtmlHelpW(
  hwndCaller: THandle;   // HWND optional
  pszFile: PWideChar;   // LPCWSTR
  uCommand: DWORD;   // DWORD
  dwData: NativeUInt   // UINT_PTR
): THandle; stdcall;
  external 'hhctrl.ocx' name 'HtmlHelpW';

result := DllCall("hhctrl.ocx\HtmlHelpW"
    , "Ptr", hwndCaller   ; HWND optional
    , "WStr", pszFile   ; LPCWSTR
    , "UInt", uCommand   ; DWORD
    , "UPtr", dwData   ; UINT_PTR
    , "Ptr")   ; return: HWND

●HtmlHelpW(hwndCaller, pszFile, uCommand, dwData) = DLL("hhctrl.ocx", "void* HtmlHelpW(void*, char*, dword, int)")
# 呼び出し: HtmlHelpW(hwndCaller, pszFile, uCommand, dwData)
# hwndCaller : HWND optional -> "void*"
# pszFile : LPCWSTR -> "char*"
# uCommand : DWORD -> "dword"
# dwData : UINT_PTR -> "int"
# 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。