SetDllDirectoryA

// KERNEL32.dll  (ANSI / -A)
#include <windows.h>

BOOL SetDllDirectoryA(
    LPCSTR lpPathName   // optional
);

<DllImport("KERNEL32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function SetDllDirectoryA(
    <MarshalAs(UnmanagedType.LPStr)> lpPathName As String   ' LPCSTR optional
) As Boolean
End Function

' lpPathName : LPCSTR optional
Declare PtrSafe Function SetDllDirectoryA Lib "kernel32" ( _
    ByVal lpPathName As String) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

SetDllDirectoryA = ctypes.windll.kernel32.SetDllDirectoryA
SetDllDirectoryA.restype = wintypes.BOOL
SetDllDirectoryA.argtypes = [
    wintypes.LPCSTR,  # lpPathName : LPCSTR optional
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('KERNEL32.dll')
SetDllDirectoryA = Fiddle::Function.new(
  lib['SetDllDirectoryA'],
  [
    Fiddle::TYPE_VOIDP,  # lpPathName : LPCSTR optional
  ],
  Fiddle::TYPE_INT)

#[link(name = "kernel32")]
extern "system" {
    fn SetDllDirectoryA(
        lpPathName: *const u8  // LPCSTR optional
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("KERNEL32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern bool SetDllDirectoryA([MarshalAs(UnmanagedType.LPStr)] string lpPathName);
"@
$api = Add-Type -MemberDefinition $sig -Name 'KERNEL32_SetDllDirectoryA' -Namespace Win32 -PassThru
# $api::SetDllDirectoryA(lpPathName)

#uselib "KERNEL32.dll"
#func global SetDllDirectoryA "SetDllDirectoryA" sptr
; SetDllDirectoryA lpPathName   ; 戻り値は stat
; lpPathName : 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 "KERNEL32.dll"
#cfunc global SetDllDirectoryA "SetDllDirectoryA" str
; res = SetDllDirectoryA(lpPathName)
; lpPathName : LPCSTR optional -> "str"

; BOOL SetDllDirectoryA(LPCSTR lpPathName)
#uselib "KERNEL32.dll"
#cfunc global SetDllDirectoryA "SetDllDirectoryA" str
; res = SetDllDirectoryA(lpPathName)
; lpPathName : LPCSTR optional -> "str"

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

var (
	kernel32 = windows.NewLazySystemDLL("KERNEL32.dll")
	procSetDllDirectoryA = kernel32.NewProc("SetDllDirectoryA")
)

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

function SetDllDirectoryA(
  lpPathName: PAnsiChar   // LPCSTR optional
): BOOL; stdcall;
  external 'KERNEL32.dll' name 'SetDllDirectoryA';

result := DllCall("KERNEL32\SetDllDirectoryA"
    , "AStr", lpPathName   ; LPCSTR optional
    , "Int")   ; return: BOOL

●SetDllDirectoryA(lpPathName) = DLL("KERNEL32.dll", "bool SetDllDirectoryA(char*)")
# 呼び出し: SetDllDirectoryA(lpPathName)
# lpPathName : 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)。