MsiQueryProductStateW

// msi.dll  (Unicode / -W)
#include <windows.h>

INSTALLSTATE MsiQueryProductStateW(
    LPCWSTR szProduct
);

<DllImport("msi.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function MsiQueryProductStateW(
    <MarshalAs(UnmanagedType.LPWStr)> szProduct As String   ' LPCWSTR
) As Integer
End Function

' szProduct : LPCWSTR
Declare PtrSafe Function MsiQueryProductStateW Lib "msi" ( _
    ByVal szProduct As LongPtr) As Long
' Unicode(W): 文字列は ByVal As LongPtr とし StrPtr(unicodeStr) を渡す
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

MsiQueryProductStateW = ctypes.windll.msi.MsiQueryProductStateW
MsiQueryProductStateW.restype = ctypes.c_int
MsiQueryProductStateW.argtypes = [
    wintypes.LPCWSTR,  # szProduct : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('msi.dll')
MsiQueryProductStateW = Fiddle::Function.new(
  lib['MsiQueryProductStateW'],
  [
    Fiddle::TYPE_VOIDP,  # szProduct : LPCWSTR
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "msi")]
extern "system" {
    fn MsiQueryProductStateW(
        szProduct: *const u16  // LPCWSTR
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("msi.dll", CharSet = CharSet.Unicode)]
public static extern int MsiQueryProductStateW([MarshalAs(UnmanagedType.LPWStr)] string szProduct);
"@
$api = Add-Type -MemberDefinition $sig -Name 'msi_MsiQueryProductStateW' -Namespace Win32 -PassThru
# $api::MsiQueryProductStateW(szProduct)

#uselib "msi.dll"
#func global MsiQueryProductStateW "MsiQueryProductStateW" wptr
; MsiQueryProductStateW szProduct   ; 戻り値は stat
; szProduct : LPCWSTR -> "wptr"
; ※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 "msi.dll"
#cfunc global MsiQueryProductStateW "MsiQueryProductStateW" wstr
; res = MsiQueryProductStateW(szProduct)
; szProduct : LPCWSTR -> "wstr"

; INSTALLSTATE MsiQueryProductStateW(LPCWSTR szProduct)
#uselib "msi.dll"
#cfunc global MsiQueryProductStateW "MsiQueryProductStateW" wstr
; res = MsiQueryProductStateW(szProduct)
; szProduct : LPCWSTR -> "wstr"

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

var (
	msi = windows.NewLazySystemDLL("msi.dll")
	procMsiQueryProductStateW = msi.NewProc("MsiQueryProductStateW")
)

// szProduct (LPCWSTR)
r1, _, err := procMsiQueryProductStateW.Call(
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(szProduct))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // INSTALLSTATE

function MsiQueryProductStateW(
  szProduct: PWideChar   // LPCWSTR
): Integer; stdcall;
  external 'msi.dll' name 'MsiQueryProductStateW';

result := DllCall("msi\MsiQueryProductStateW"
    , "WStr", szProduct   ; LPCWSTR
    , "Int")   ; return: INSTALLSTATE

●MsiQueryProductStateW(szProduct) = DLL("msi.dll", "int MsiQueryProductStateW(char*)")
# 呼び出し: MsiQueryProductStateW(szProduct)
# szProduct : LPCWSTR -> "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)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。