CharToOemA

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

BOOL CharToOemA(
    LPCSTR pSrc,
    LPSTR pDst
);

<DllImport("USER32.dll", CharSet:=CharSet.Ansi, SetLastError:=True, ExactSpelling:=True)>
Public Shared Function CharToOemA(
    <MarshalAs(UnmanagedType.LPStr)> pSrc As String,   ' LPCSTR
    <MarshalAs(UnmanagedType.LPStr)> pDst As System.Text.StringBuilder   ' LPSTR out
) As Boolean
End Function

' pSrc : LPCSTR
' pDst : LPSTR out
Declare PtrSafe Function CharToOemA Lib "user32" ( _
    ByVal pSrc As String, _
    ByVal pDst 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

CharToOemA = ctypes.windll.user32.CharToOemA
CharToOemA.restype = wintypes.BOOL
CharToOemA.argtypes = [
    wintypes.LPCSTR,  # pSrc : LPCSTR
    wintypes.LPSTR,  # pDst : LPSTR out
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('USER32.dll')
CharToOemA = Fiddle::Function.new(
  lib['CharToOemA'],
  [
    Fiddle::TYPE_VOIDP,  # pSrc : LPCSTR
    Fiddle::TYPE_VOIDP,  # pDst : LPSTR out
  ],
  Fiddle::TYPE_INT)

#[link(name = "user32")]
extern "system" {
    fn CharToOemA(
        pSrc: *const u8,  // LPCSTR
        pDst: *mut u8  // LPSTR out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("USER32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
public static extern bool CharToOemA([MarshalAs(UnmanagedType.LPStr)] string pSrc, [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder pDst);
"@
$api = Add-Type -MemberDefinition $sig -Name 'USER32_CharToOemA' -Namespace Win32 -PassThru
# $api::CharToOemA(pSrc, pDst)

#uselib "USER32.dll"
#func global CharToOemA "CharToOemA" sptr, sptr
; CharToOemA pSrc, varptr(pDst)   ; 戻り値は stat
; pSrc : LPCSTR -> "sptr"
; pDst : LPSTR 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 CharToOemA "CharToOemA" str, var
; res = CharToOemA(pSrc, pDst)
; pSrc : LPCSTR -> "str"
; pDst : LPSTR 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。

; BOOL CharToOemA(LPCSTR pSrc, LPSTR pDst)
#uselib "USER32.dll"
#cfunc global CharToOemA "CharToOemA" str, var
; res = CharToOemA(pSrc, pDst)
; pSrc : LPCSTR -> "str"
; pDst : LPSTR 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")
	procCharToOemA = user32.NewProc("CharToOemA")
)

// pSrc (LPCSTR), pDst (LPSTR out)
r1, _, err := procCharToOemA.Call(
	uintptr(unsafe.Pointer(windows.BytePtrFromString(pSrc))),
	uintptr(pDst),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // BOOL

function CharToOemA(
  pSrc: PAnsiChar;   // LPCSTR
  pDst: PAnsiChar   // LPSTR out
): BOOL; stdcall;
  external 'USER32.dll' name 'CharToOemA';

result := DllCall("USER32\CharToOemA"
    , "AStr", pSrc   ; LPCSTR
    , "Ptr", pDst   ; LPSTR out
    , "Int")   ; return: BOOL

●CharToOemA(pSrc, pDst) = DLL("USER32.dll", "bool CharToOemA(char*, char*)")
# 呼び出し: CharToOemA(pSrc, pDst)
# pSrc : LPCSTR -> "char*"
# pDst : LPSTR out -> "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)。