FindWindowA

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

HWND FindWindowA(
    LPCSTR lpClassName,   // optional
    LPCSTR lpWindowName   // optional
);

<DllImport("USER32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function FindWindowA(
    <MarshalAs(UnmanagedType.LPStr)> lpClassName As String,   ' LPCSTR optional
    <MarshalAs(UnmanagedType.LPStr)> lpWindowName As String   ' LPCSTR optional
) As IntPtr
End Function

' lpClassName : LPCSTR optional
' lpWindowName : LPCSTR optional
Declare PtrSafe Function FindWindowA Lib "user32" ( _
    ByVal lpClassName As String, _
    ByVal lpWindowName As String) As LongPtr
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

FindWindowA = ctypes.windll.user32.FindWindowA
FindWindowA.restype = ctypes.c_void_p
FindWindowA.argtypes = [
    wintypes.LPCSTR,  # lpClassName : LPCSTR optional
    wintypes.LPCSTR,  # lpWindowName : LPCSTR optional
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
FindWindowA = Fiddle::Function.new(
  lib['FindWindowA'],
  [
    Fiddle::TYPE_VOIDP,  # lpClassName : LPCSTR optional
    Fiddle::TYPE_VOIDP,  # lpWindowName : LPCSTR optional
  ],
  Fiddle::TYPE_VOIDP)

#[link(name = "user32")]
extern "system" {
    fn FindWindowA(
        lpClassName: *const u8,  // LPCSTR optional
        lpWindowName: *const u8  // LPCSTR optional
    ) -> *mut core::ffi::c_void;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("USER32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern IntPtr FindWindowA([MarshalAs(UnmanagedType.LPStr)] string lpClassName, [MarshalAs(UnmanagedType.LPStr)] string lpWindowName);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_FindWindowA' -Namespace Win32 -PassThru
# $api::FindWindowA(lpClassName, lpWindowName)

#uselib "USER32.dll"
#func global FindWindowA "FindWindowA" sptr, sptr
; FindWindowA lpClassName, lpWindowName   ; 戻り値は stat
; lpClassName : LPCSTR optional -> "sptr"
; lpWindowName : LPCSTR optional -> "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 FindWindowA "FindWindowA" str, str
; res = FindWindowA(lpClassName, lpWindowName)
; lpClassName : LPCSTR optional -> "str"
; lpWindowName : LPCSTR optional -> "str"

; HWND FindWindowA(LPCSTR lpClassName, LPCSTR lpWindowName)
#uselib "USER32.dll"
#cfunc global FindWindowA "FindWindowA" str, str
; res = FindWindowA(lpClassName, lpWindowName)
; lpClassName : LPCSTR optional -> "str"
; lpWindowName : LPCSTR optional -> "str"

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

var (
	user32 = windows.NewLazySystemDLL("USER32.dll")
	procFindWindowA = user32.NewProc("FindWindowA")
)

// lpClassName (LPCSTR optional), lpWindowName (LPCSTR optional)
r1, _, err := procFindWindowA.Call(
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpClassName))),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(lpWindowName))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HWND

function FindWindowA(
  lpClassName: PAnsiChar;   // LPCSTR optional
  lpWindowName: PAnsiChar   // LPCSTR optional
): THandle; stdcall;
  external 'USER32.dll' name 'FindWindowA';

result := DllCall("USER32\FindWindowA"
    , "AStr", lpClassName   ; LPCSTR optional
    , "AStr", lpWindowName   ; LPCSTR optional
    , "Ptr")   ; return: HWND

●FindWindowA(lpClassName, lpWindowName) = DLL("USER32.dll", "void* FindWindowA(char*, char*)")
# 呼び出し: FindWindowA(lpClassName, lpWindowName)
# lpClassName : LPCSTR optional -> "char*"
# lpWindowName : LPCSTR optional -> "char*"
# 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)。