GetWindowThreadProcessId

// USER32.dll
#include <windows.h>

DWORD GetWindowThreadProcessId(
    HWND hWnd,
    DWORD* lpdwProcessId   // optional
);

<DllImport("USER32.dll", ExactSpelling:=True)>
Public Shared Function GetWindowThreadProcessId(
    hWnd As IntPtr,   ' HWND
    lpdwProcessId As IntPtr   ' DWORD* optional, out
) As UInteger
End Function

' hWnd : HWND
' lpdwProcessId : DWORD* optional, out
Declare PtrSafe Function GetWindowThreadProcessId Lib "user32" ( _
    ByVal hWnd As LongPtr, _
    ByVal lpdwProcessId 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

GetWindowThreadProcessId = ctypes.windll.user32.GetWindowThreadProcessId
GetWindowThreadProcessId.restype = wintypes.DWORD
GetWindowThreadProcessId.argtypes = [
    wintypes.HANDLE,  # hWnd : HWND
    ctypes.POINTER(wintypes.DWORD),  # lpdwProcessId : DWORD* optional, out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
GetWindowThreadProcessId = Fiddle::Function.new(
  lib['GetWindowThreadProcessId'],
  [
    Fiddle::TYPE_VOIDP,  # hWnd : HWND
    Fiddle::TYPE_VOIDP,  # lpdwProcessId : DWORD* optional, out
  ],
  -Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn GetWindowThreadProcessId(
        hWnd: *mut core::ffi::c_void,  // HWND
        lpdwProcessId: *mut u32  // DWORD* optional, out
    ) -> u32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll")]
public static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr lpdwProcessId);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_GetWindowThreadProcessId' -Namespace Win32 -PassThru
# $api::GetWindowThreadProcessId(hWnd, lpdwProcessId)

#uselib "USER32.dll"
#func global GetWindowThreadProcessId "GetWindowThreadProcessId" sptr, sptr
; GetWindowThreadProcessId hWnd, varptr(lpdwProcessId)   ; 戻り値は stat
; hWnd : HWND -> "sptr"
; lpdwProcessId : DWORD* optional, 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 "USER32.dll"
#cfunc global GetWindowThreadProcessId "GetWindowThreadProcessId" sptr, var
; res = GetWindowThreadProcessId(hWnd, lpdwProcessId)
; hWnd : HWND -> "sptr"
; lpdwProcessId : DWORD* optional, 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。

; DWORD GetWindowThreadProcessId(HWND hWnd, DWORD* lpdwProcessId)
#uselib "USER32.dll"
#cfunc global GetWindowThreadProcessId "GetWindowThreadProcessId" intptr, var
; res = GetWindowThreadProcessId(hWnd, lpdwProcessId)
; hWnd : HWND -> "intptr"
; lpdwProcessId : DWORD* optional, 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 (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procGetWindowThreadProcessId = user32.NewProc("GetWindowThreadProcessId")
)

// hWnd (HWND), lpdwProcessId (DWORD* optional, out)
r1, _, err := procGetWindowThreadProcessId.Call(
	uintptr(hWnd),
	uintptr(lpdwProcessId),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // DWORD

function GetWindowThreadProcessId(
  hWnd: THandle;   // HWND
  lpdwProcessId: Pointer   // DWORD* optional, out
): DWORD; stdcall;
  external 'USER32.dll' name 'GetWindowThreadProcessId';

result := DllCall("USER32\GetWindowThreadProcessId"
    , "Ptr", hWnd   ; HWND
    , "Ptr", lpdwProcessId   ; DWORD* optional, out
    , "UInt")   ; return: DWORD

●GetWindowThreadProcessId(hWnd, lpdwProcessId) = DLL("USER32.dll", "dword GetWindowThreadProcessId(void*, void*)")
# 呼び出し: GetWindowThreadProcessId(hWnd, lpdwProcessId)
# hWnd : HWND -> "void*"
# lpdwProcessId : DWORD* optional, 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)。