RegOpenKeyA

// ADVAPI32.dll  (ANSI / -A)
#include <windows.h>

WIN32_ERROR RegOpenKeyA(
    HKEY hKey,
    LPCSTR lpSubKey,   // optional
    HKEY* phkResult
);

<DllImport("ADVAPI32.dll", CharSet:=CharSet.Ansi, ExactSpelling:=True)>
Public Shared Function RegOpenKeyA(
    hKey As IntPtr,   ' HKEY
    <MarshalAs(UnmanagedType.LPStr)> lpSubKey As String,   ' LPCSTR optional
    phkResult As IntPtr   ' HKEY* out
) As UInteger
End Function

' hKey : HKEY
' lpSubKey : LPCSTR optional
' phkResult : HKEY* out
Declare PtrSafe Function RegOpenKeyA Lib "advapi32" ( _
    ByVal hKey As LongPtr, _
    ByVal lpSubKey As String, _
    ByVal phkResult As LongPtr) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

RegOpenKeyA = ctypes.windll.advapi32.RegOpenKeyA
RegOpenKeyA.restype = wintypes.DWORD
RegOpenKeyA.argtypes = [
    wintypes.HANDLE,  # hKey : HKEY
    wintypes.LPCSTR,  # lpSubKey : LPCSTR optional
    ctypes.c_void_p,  # phkResult : HKEY* out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('ADVAPI32.dll')
RegOpenKeyA = Fiddle::Function.new(
  lib['RegOpenKeyA'],
  [
    Fiddle::TYPE_VOIDP,  # hKey : HKEY
    Fiddle::TYPE_VOIDP,  # lpSubKey : LPCSTR optional
    Fiddle::TYPE_VOIDP,  # phkResult : HKEY* out
  ],
  -Fiddle::TYPE_INT)

#[link(name = "advapi32")]
extern "system" {
    fn RegOpenKeyA(
        hKey: *mut core::ffi::c_void,  // HKEY
        lpSubKey: *const u8,  // LPCSTR optional
        phkResult: *mut *mut core::ffi::c_void  // HKEY* out
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("ADVAPI32.dll", CharSet = CharSet.Ansi)]
public static extern uint RegOpenKeyA(IntPtr hKey, [MarshalAs(UnmanagedType.LPStr)] string lpSubKey, IntPtr phkResult);
"@
$api = Add-Type -MemberDefinition $sig -Name 'ADVAPI32_RegOpenKeyA' -Namespace Win32 -PassThru
# $api::RegOpenKeyA(hKey, lpSubKey, phkResult)

#uselib "ADVAPI32.dll"
#func global RegOpenKeyA "RegOpenKeyA" sptr, sptr, sptr
; RegOpenKeyA hKey, lpSubKey, phkResult   ; 戻り値は stat
; hKey : HKEY -> "sptr"
; lpSubKey : LPCSTR optional -> "sptr"
; phkResult : HKEY* out -> "sptr"
; ※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 "ADVAPI32.dll"
#cfunc global RegOpenKeyA "RegOpenKeyA" sptr, str, sptr
; res = RegOpenKeyA(hKey, lpSubKey, phkResult)
; hKey : HKEY -> "sptr"
; lpSubKey : LPCSTR optional -> "str"
; phkResult : HKEY* out -> "sptr"

; WIN32_ERROR RegOpenKeyA(HKEY hKey, LPCSTR lpSubKey, HKEY* phkResult)
#uselib "ADVAPI32.dll"
#cfunc global RegOpenKeyA "RegOpenKeyA" intptr, str, intptr
; res = RegOpenKeyA(hKey, lpSubKey, phkResult)
; hKey : HKEY -> "intptr"
; lpSubKey : LPCSTR optional -> "str"
; phkResult : HKEY* out -> "intptr"

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

var (
	advapi32 = windows.NewLazySystemDLL("ADVAPI32.dll")
	procRegOpenKeyA = advapi32.NewProc("RegOpenKeyA")
)

// hKey (HKEY), lpSubKey (LPCSTR optional), phkResult (HKEY* out)
r1, _, err := procRegOpenKeyA.Call(
	uintptr(hKey),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpSubKey))),
	uintptr(phkResult),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // WIN32_ERROR

function RegOpenKeyA(
  hKey: THandle;   // HKEY
  lpSubKey: PAnsiChar;   // LPCSTR optional
  phkResult: Pointer   // HKEY* out
): DWORD; stdcall;
  external 'ADVAPI32.dll' name 'RegOpenKeyA';

result := DllCall("ADVAPI32\RegOpenKeyA"
    , "Ptr", hKey   ; HKEY
    , "AStr", lpSubKey   ; LPCSTR optional
    , "Ptr", phkResult   ; HKEY* out
    , "UInt")   ; return: WIN32_ERROR

●RegOpenKeyA(hKey, lpSubKey, phkResult) = DLL("ADVAPI32.dll", "dword RegOpenKeyA(void*, char*, void*)")
# 呼び出し: RegOpenKeyA(hKey, lpSubKey, phkResult)
# hKey : HKEY -> "void*"
# lpSubKey : LPCSTR optional -> "char*"
# phkResult : HKEY* out -> "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)。