SetDefaultPrinterW

// winspool.drv  (Unicode / -W)
#include <windows.h>

BOOL SetDefaultPrinterW(
    LPCWSTR pszPrinter   // optional
);

<DllImport("winspool.drv", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function SetDefaultPrinterW(
    <MarshalAs(UnmanagedType.LPWStr)> pszPrinter As String   ' LPCWSTR optional
) As Boolean
End Function

' pszPrinter : LPCWSTR optional
Declare PtrSafe Function SetDefaultPrinterW Lib "winspool.drv" ( _
    ByVal pszPrinter 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

SetDefaultPrinterW = ctypes.windll.LoadLibrary("winspool.drv").SetDefaultPrinterW
SetDefaultPrinterW.restype = wintypes.BOOL
SetDefaultPrinterW.argtypes = [
    wintypes.LPCWSTR,  # pszPrinter : LPCWSTR optional
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('winspool.drv')
SetDefaultPrinterW = Fiddle::Function.new(
  lib['SetDefaultPrinterW'],
  [
    Fiddle::TYPE_VOIDP,  # pszPrinter : LPCWSTR optional
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

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

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("winspool.drv", CharSet = CharSet.Unicode)]
public static extern bool SetDefaultPrinterW([MarshalAs(UnmanagedType.LPWStr)] string pszPrinter);
"@
$api = Add-Type -MemberDefinition $sig -Name 'winspool.drv_SetDefaultPrinterW' -Namespace Win32 -PassThru
# $api::SetDefaultPrinterW(pszPrinter)

#uselib "winspool.drv"
#func global SetDefaultPrinterW "SetDefaultPrinterW" wptr
; SetDefaultPrinterW pszPrinter   ; 戻り値は stat
; pszPrinter : LPCWSTR optional -> "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 "winspool.drv"
#cfunc global SetDefaultPrinterW "SetDefaultPrinterW" wstr
; res = SetDefaultPrinterW(pszPrinter)
; pszPrinter : LPCWSTR optional -> "wstr"

; BOOL SetDefaultPrinterW(LPCWSTR pszPrinter)
#uselib "winspool.drv"
#cfunc global SetDefaultPrinterW "SetDefaultPrinterW" wstr
; res = SetDefaultPrinterW(pszPrinter)
; pszPrinter : LPCWSTR optional -> "wstr"

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

var (
	winspool_drv = windows.NewLazySystemDLL("winspool.drv")
	procSetDefaultPrinterW = winspool_drv.NewProc("SetDefaultPrinterW")
)

// pszPrinter (LPCWSTR optional)
r1, _, err := procSetDefaultPrinterW.Call(
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszPrinter))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function SetDefaultPrinterW(
  pszPrinter: PWideChar   // LPCWSTR optional
): BOOL; stdcall;
  external 'winspool.drv' name 'SetDefaultPrinterW';

result := DllCall("winspool.drv\SetDefaultPrinterW"
    , "WStr", pszPrinter   ; LPCWSTR optional
    , "Int")   ; return: BOOL

●SetDefaultPrinterW(pszPrinter) = DLL("winspool.drv", "bool SetDefaultPrinterW(char*)")
# 呼び出し: SetDefaultPrinterW(pszPrinter)
# pszPrinter : LPCWSTR 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)。
# ※-W(Unicode)関数。なでしこ1はANSIのため -A 版の利用を推奨。