VarWeekdayName

// OLEAUT32.dll
#include <windows.h>

HRESULT VarWeekdayName(
    INT iWeekday,
    INT fAbbrev,
    INT iFirstDay,
    DWORD dwFlags,
    LPWSTR* pbstrOut
);

<DllImport("OLEAUT32.dll", ExactSpelling:=True)>
Public Shared Function VarWeekdayName(
    iWeekday As Integer,   ' INT
    fAbbrev As Integer,   ' INT
    iFirstDay As Integer,   ' INT
    dwFlags As UInteger,   ' DWORD
    pbstrOut As IntPtr   ' LPWSTR* out
) As Integer
End Function

' iWeekday : INT
' fAbbrev : INT
' iFirstDay : INT
' dwFlags : DWORD
' pbstrOut : LPWSTR* out
Declare PtrSafe Function VarWeekdayName Lib "oleaut32" ( _
    ByVal iWeekday As Long, _
    ByVal fAbbrev As Long, _
    ByVal iFirstDay As Long, _
    ByVal dwFlags As Long, _
    ByVal pbstrOut 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

VarWeekdayName = ctypes.windll.oleaut32.VarWeekdayName
VarWeekdayName.restype = ctypes.c_int
VarWeekdayName.argtypes = [
    ctypes.c_int,  # iWeekday : INT
    ctypes.c_int,  # fAbbrev : INT
    ctypes.c_int,  # iFirstDay : INT
    wintypes.DWORD,  # dwFlags : DWORD
    ctypes.c_void_p,  # pbstrOut : LPWSTR* out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('OLEAUT32.dll')
VarWeekdayName = Fiddle::Function.new(
  lib['VarWeekdayName'],
  [
    Fiddle::TYPE_INT,  # iWeekday : INT
    Fiddle::TYPE_INT,  # fAbbrev : INT
    Fiddle::TYPE_INT,  # iFirstDay : INT
    -Fiddle::TYPE_INT,  # dwFlags : DWORD
    Fiddle::TYPE_VOIDP,  # pbstrOut : LPWSTR* out
  ],
  Fiddle::TYPE_INT)

#[link(name = "oleaut32")]
extern "system" {
    fn VarWeekdayName(
        iWeekday: i32,  // INT
        fAbbrev: i32,  // INT
        iFirstDay: i32,  // INT
        dwFlags: u32,  // DWORD
        pbstrOut: *mut *mut u16  // LPWSTR* out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("OLEAUT32.dll")]
public static extern int VarWeekdayName(int iWeekday, int fAbbrev, int iFirstDay, uint dwFlags, IntPtr pbstrOut);
"@
$api = Add-Type -MemberDefinition $sig -Name 'OLEAUT32_VarWeekdayName' -Namespace Win32 -PassThru
# $api::VarWeekdayName(iWeekday, fAbbrev, iFirstDay, dwFlags, pbstrOut)

#uselib "OLEAUT32.dll"
#func global VarWeekdayName "VarWeekdayName" sptr, sptr, sptr, sptr, sptr
; VarWeekdayName iWeekday, fAbbrev, iFirstDay, dwFlags, varptr(pbstrOut)   ; 戻り値は stat
; iWeekday : INT -> "sptr"
; fAbbrev : INT -> "sptr"
; iFirstDay : INT -> "sptr"
; dwFlags : DWORD -> "sptr"
; pbstrOut : LPWSTR* 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 "OLEAUT32.dll"
#cfunc global VarWeekdayName "VarWeekdayName" int, int, int, int, var
; res = VarWeekdayName(iWeekday, fAbbrev, iFirstDay, dwFlags, pbstrOut)
; iWeekday : INT -> "int"
; fAbbrev : INT -> "int"
; iFirstDay : INT -> "int"
; dwFlags : DWORD -> "int"
; pbstrOut : LPWSTR* out -> "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。

; HRESULT VarWeekdayName(INT iWeekday, INT fAbbrev, INT iFirstDay, DWORD dwFlags, LPWSTR* pbstrOut)
#uselib "OLEAUT32.dll"
#cfunc global VarWeekdayName "VarWeekdayName" int, int, int, int, var
; res = VarWeekdayName(iWeekday, fAbbrev, iFirstDay, dwFlags, pbstrOut)
; iWeekday : INT -> "int"
; fAbbrev : INT -> "int"
; iFirstDay : INT -> "int"
; dwFlags : DWORD -> "int"
; pbstrOut : LPWSTR* out -> "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 (
	oleaut32 = windows.NewLazySystemDLL("OLEAUT32.dll")
	procVarWeekdayName = oleaut32.NewProc("VarWeekdayName")
)

// iWeekday (INT), fAbbrev (INT), iFirstDay (INT), dwFlags (DWORD), pbstrOut (LPWSTR* out)
r1, _, err := procVarWeekdayName.Call(
	uintptr(iWeekday),
	uintptr(fAbbrev),
	uintptr(iFirstDay),
	uintptr(dwFlags),
	uintptr(pbstrOut),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT

function VarWeekdayName(
  iWeekday: Integer;   // INT
  fAbbrev: Integer;   // INT
  iFirstDay: Integer;   // INT
  dwFlags: DWORD;   // DWORD
  pbstrOut: PPWideChar   // LPWSTR* out
): Integer; stdcall;
  external 'OLEAUT32.dll' name 'VarWeekdayName';

result := DllCall("OLEAUT32\VarWeekdayName"
    , "Int", iWeekday   ; INT
    , "Int", fAbbrev   ; INT
    , "Int", iFirstDay   ; INT
    , "UInt", dwFlags   ; DWORD
    , "Ptr", pbstrOut   ; LPWSTR* out
    , "Int")   ; return: HRESULT

●VarWeekdayName(iWeekday, fAbbrev, iFirstDay, dwFlags, pbstrOut) = DLL("OLEAUT32.dll", "int VarWeekdayName(int, int, int, dword, void*)")
# 呼び出し: VarWeekdayName(iWeekday, fAbbrev, iFirstDay, dwFlags, pbstrOut)
# iWeekday : INT -> "int"
# fAbbrev : INT -> "int"
# iFirstDay : INT -> "int"
# dwFlags : DWORD -> "dword"
# pbstrOut : LPWSTR* 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)。