SetClassLongA

// USER32.dll  (ANSI / -A)
#include <windows.h>

DWORD SetClassLongA(
    HWND hWnd,
    GET_CLASS_LONG_INDEX nIndex,
    INT dwNewLong
);

<DllImport("USER32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function SetClassLongA(
    hWnd As IntPtr,   ' HWND
    nIndex As Integer,   ' GET_CLASS_LONG_INDEX
    dwNewLong As Integer   ' INT
) As UInteger
End Function

' hWnd : HWND
' nIndex : GET_CLASS_LONG_INDEX
' dwNewLong : INT
Declare PtrSafe Function SetClassLongA Lib "user32" ( _
    ByVal hWnd As LongPtr, _
    ByVal nIndex As Long, _
    ByVal dwNewLong 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

SetClassLongA = ctypes.windll.user32.SetClassLongA
SetClassLongA.restype = wintypes.DWORD
SetClassLongA.argtypes = [
    wintypes.HANDLE,  # hWnd : HWND
    ctypes.c_int,  # nIndex : GET_CLASS_LONG_INDEX
    ctypes.c_int,  # dwNewLong : INT
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
SetClassLongA = Fiddle::Function.new(
  lib['SetClassLongA'],
  [
    Fiddle::TYPE_VOIDP,  # hWnd : HWND
    Fiddle::TYPE_INT,  # nIndex : GET_CLASS_LONG_INDEX
    Fiddle::TYPE_INT,  # dwNewLong : INT
  ],
  -Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn SetClassLongA(
        hWnd: *mut core::ffi::c_void,  // HWND
        nIndex: i32,  // GET_CLASS_LONG_INDEX
        dwNewLong: i32  // INT
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern uint SetClassLongA(IntPtr hWnd, int nIndex, int dwNewLong);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_SetClassLongA' -Namespace Win32 -PassThru
# $api::SetClassLongA(hWnd, nIndex, dwNewLong)

#uselib "USER32.dll"
#func global SetClassLongA "SetClassLongA" sptr, sptr, sptr
; SetClassLongA hWnd, nIndex, dwNewLong   ; 戻り値は stat
; hWnd : HWND -> "sptr"
; nIndex : GET_CLASS_LONG_INDEX -> "sptr"
; dwNewLong : INT -> "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 "USER32.dll"
#cfunc global SetClassLongA "SetClassLongA" sptr, int, int
; res = SetClassLongA(hWnd, nIndex, dwNewLong)
; hWnd : HWND -> "sptr"
; nIndex : GET_CLASS_LONG_INDEX -> "int"
; dwNewLong : INT -> "int"

; DWORD SetClassLongA(HWND hWnd, GET_CLASS_LONG_INDEX nIndex, INT dwNewLong)
#uselib "USER32.dll"
#cfunc global SetClassLongA "SetClassLongA" intptr, int, int
; res = SetClassLongA(hWnd, nIndex, dwNewLong)
; hWnd : HWND -> "intptr"
; nIndex : GET_CLASS_LONG_INDEX -> "int"
; dwNewLong : INT -> "int"

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

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procSetClassLongA = user32.NewProc("SetClassLongA")
)

// hWnd (HWND), nIndex (GET_CLASS_LONG_INDEX), dwNewLong (INT)
r1, _, err := procSetClassLongA.Call(
	uintptr(hWnd),
	uintptr(nIndex),
	uintptr(dwNewLong),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function SetClassLongA(
  hWnd: THandle;   // HWND
  nIndex: Integer;   // GET_CLASS_LONG_INDEX
  dwNewLong: Integer   // INT
): DWORD; stdcall;
  external 'USER32.dll' name 'SetClassLongA';

result := DllCall("USER32\SetClassLongA"
    , "Ptr", hWnd   ; HWND
    , "Int", nIndex   ; GET_CLASS_LONG_INDEX
    , "Int", dwNewLong   ; INT
    , "UInt")   ; return: DWORD

●SetClassLongA(hWnd, nIndex, dwNewLong) = DLL("USER32.dll", "dword SetClassLongA(void*, int, int)")
# 呼び出し: SetClassLongA(hWnd, nIndex, dwNewLong)
# hWnd : HWND -> "void*"
# nIndex : GET_CLASS_LONG_INDEX -> "int"
# dwNewLong : INT -> "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)。