RegEnumKeyA

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

WIN32_ERROR RegEnumKeyA(
    HKEY hKey,
    DWORD dwIndex,
    LPSTR lpName,   // optional
    DWORD cchName
);

<DllImport("ADVAPI32.dll", CharSet:=CharSet.Ansi, ExactSpelling:=True)>
Public Shared Function RegEnumKeyA(
    hKey As IntPtr,   ' HKEY
    dwIndex As UInteger,   ' DWORD
    <MarshalAs(UnmanagedType.LPStr)> lpName As System.Text.StringBuilder,   ' LPSTR optional, out
    cchName As UInteger   ' DWORD
) As UInteger
End Function

' hKey : HKEY
' dwIndex : DWORD
' lpName : LPSTR optional, out
' cchName : DWORD
Declare PtrSafe Function RegEnumKeyA Lib "advapi32" ( _
    ByVal hKey As LongPtr, _
    ByVal dwIndex As Long, _
    ByVal lpName As String, _
    ByVal cchName As Long) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

RegEnumKeyA = ctypes.windll.advapi32.RegEnumKeyA
RegEnumKeyA.restype = wintypes.DWORD
RegEnumKeyA.argtypes = [
    wintypes.HANDLE,  # hKey : HKEY
    wintypes.DWORD,  # dwIndex : DWORD
    wintypes.LPSTR,  # lpName : LPSTR optional, out
    wintypes.DWORD,  # cchName : DWORD
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('ADVAPI32.dll')
RegEnumKeyA = Fiddle::Function.new(
  lib['RegEnumKeyA'],
  [
    Fiddle::TYPE_VOIDP,  # hKey : HKEY
    -Fiddle::TYPE_INT,  # dwIndex : DWORD
    Fiddle::TYPE_VOIDP,  # lpName : LPSTR optional, out
    -Fiddle::TYPE_INT,  # cchName : DWORD
  ],
  -Fiddle::TYPE_INT)

#[link(name = "advapi32")]
extern "system" {
    fn RegEnumKeyA(
        hKey: *mut core::ffi::c_void,  // HKEY
        dwIndex: u32,  // DWORD
        lpName: *mut u8,  // LPSTR optional, out
        cchName: u32  // DWORD
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("ADVAPI32.dll", CharSet = CharSet.Ansi)]
public static extern uint RegEnumKeyA(IntPtr hKey, uint dwIndex, [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder lpName, uint cchName);
"@
$api = Add-Type -MemberDefinition $sig -Name 'ADVAPI32_RegEnumKeyA' -Namespace Win32 -PassThru
# $api::RegEnumKeyA(hKey, dwIndex, lpName, cchName)

#uselib "ADVAPI32.dll"
#func global RegEnumKeyA "RegEnumKeyA" sptr, sptr, sptr, sptr
; RegEnumKeyA hKey, dwIndex, varptr(lpName), cchName   ; 戻り値は stat
; hKey : HKEY -> "sptr"
; dwIndex : DWORD -> "sptr"
; lpName : LPSTR optional, out -> "sptr"
; cchName : DWORD -> "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 RegEnumKeyA "RegEnumKeyA" sptr, int, var, int
; res = RegEnumKeyA(hKey, dwIndex, lpName, cchName)
; hKey : HKEY -> "sptr"
; dwIndex : DWORD -> "int"
; lpName : LPSTR optional, out -> "var"
; cchName : DWORD -> "int"
; ※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。

; WIN32_ERROR RegEnumKeyA(HKEY hKey, DWORD dwIndex, LPSTR lpName, DWORD cchName)
#uselib "ADVAPI32.dll"
#cfunc global RegEnumKeyA "RegEnumKeyA" intptr, int, var, int
; res = RegEnumKeyA(hKey, dwIndex, lpName, cchName)
; hKey : HKEY -> "intptr"
; dwIndex : DWORD -> "int"
; lpName : LPSTR optional, out -> "var"
; cchName : DWORD -> "int"
; ※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 (
	advapi32 = windows.NewLazySystemDLL("ADVAPI32.dll")
	procRegEnumKeyA = advapi32.NewProc("RegEnumKeyA")
)

// hKey (HKEY), dwIndex (DWORD), lpName (LPSTR optional, out), cchName (DWORD)
r1, _, err := procRegEnumKeyA.Call(
	uintptr(hKey),
	uintptr(dwIndex),
	uintptr(lpName),
	uintptr(cchName),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // WIN32_ERROR

function RegEnumKeyA(
  hKey: THandle;   // HKEY
  dwIndex: DWORD;   // DWORD
  lpName: PAnsiChar;   // LPSTR optional, out
  cchName: DWORD   // DWORD
): DWORD; stdcall;
  external 'ADVAPI32.dll' name 'RegEnumKeyA';

result := DllCall("ADVAPI32\RegEnumKeyA"
    , "Ptr", hKey   ; HKEY
    , "UInt", dwIndex   ; DWORD
    , "Ptr", lpName   ; LPSTR optional, out
    , "UInt", cchName   ; DWORD
    , "UInt")   ; return: WIN32_ERROR

●RegEnumKeyA(hKey, dwIndex, lpName, cchName) = DLL("ADVAPI32.dll", "dword RegEnumKeyA(void*, dword, char*, dword)")
# 呼び出し: RegEnumKeyA(hKey, dwIndex, lpName, cchName)
# hKey : HKEY -> "void*"
# dwIndex : DWORD -> "dword"
# lpName : LPSTR optional, out -> "char*"
# cchName : DWORD -> "dword"
# 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)。