PathCchAddExtension

// api-ms-win-core-path-l1-1-0.dll
#include <windows.h>

HRESULT PathCchAddExtension(
    LPWSTR pszPath,
    UINT_PTR cchPath,
    LPCWSTR pszExt
);

<DllImport("api-ms-win-core-path-l1-1-0.dll", ExactSpelling:=True)>
Public Shared Function PathCchAddExtension(
    <MarshalAs(UnmanagedType.LPWStr)> pszPath As System.Text.StringBuilder,   ' LPWSTR in/out
    cchPath As UIntPtr,   ' UINT_PTR
    <MarshalAs(UnmanagedType.LPWStr)> pszExt As String   ' LPCWSTR
) As Integer
End Function

' pszPath : LPWSTR in/out
' cchPath : UINT_PTR
' pszExt : LPCWSTR
Declare PtrSafe Function PathCchAddExtension Lib "api-ms-win-core-path-l1-1-0" ( _
    ByVal pszPath As LongPtr, _
    ByVal cchPath As LongPtr, _
    ByVal pszExt As LongPtr) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

PathCchAddExtension = ctypes.windll.LoadLibrary("api-ms-win-core-path-l1-1-0.dll").PathCchAddExtension
PathCchAddExtension.restype = ctypes.c_int
PathCchAddExtension.argtypes = [
    wintypes.LPWSTR,  # pszPath : LPWSTR in/out
    ctypes.c_size_t,  # cchPath : UINT_PTR
    wintypes.LPCWSTR,  # pszExt : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('api-ms-win-core-path-l1-1-0.dll')
PathCchAddExtension = Fiddle::Function.new(
  lib['PathCchAddExtension'],
  [
    Fiddle::TYPE_VOIDP,  # pszPath : LPWSTR in/out
    Fiddle::TYPE_UINTPTR_T,  # cchPath : UINT_PTR
    Fiddle::TYPE_VOIDP,  # pszExt : LPCWSTR
  ],
  Fiddle::TYPE_INT)

#[link(name = "api-ms-win-core-path-l1-1-0")]
extern "system" {
    fn PathCchAddExtension(
        pszPath: *mut u16,  // LPWSTR in/out
        cchPath: usize,  // UINT_PTR
        pszExt: *const u16  // LPCWSTR
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("api-ms-win-core-path-l1-1-0.dll")]
public static extern int PathCchAddExtension([MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder pszPath, UIntPtr cchPath, [MarshalAs(UnmanagedType.LPWStr)] string pszExt);
"@
$api = Add-Type -MemberDefinition $sig -Name 'api-ms-win-core-path-l1-1-0_PathCchAddExtension' -Namespace Win32 -PassThru
# $api::PathCchAddExtension(pszPath, cchPath, pszExt)

#uselib "api-ms-win-core-path-l1-1-0.dll"
#func global PathCchAddExtension "PathCchAddExtension" sptr, sptr, sptr
; PathCchAddExtension varptr(pszPath), cchPath, pszExt   ; 戻り値は stat
; pszPath : LPWSTR in/out -> "sptr"
; cchPath : UINT_PTR -> "sptr"
; pszExt : LPCWSTR -> "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 "api-ms-win-core-path-l1-1-0.dll"
#cfunc global PathCchAddExtension "PathCchAddExtension" var, sptr, wstr
; res = PathCchAddExtension(pszPath, cchPath, pszExt)
; pszPath : LPWSTR in/out -> "var"
; cchPath : UINT_PTR -> "sptr"
; pszExt : LPCWSTR -> "wstr"
; ※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。

; HRESULT PathCchAddExtension(LPWSTR pszPath, UINT_PTR cchPath, LPCWSTR pszExt)
#uselib "api-ms-win-core-path-l1-1-0.dll"
#cfunc global PathCchAddExtension "PathCchAddExtension" var, intptr, wstr
; res = PathCchAddExtension(pszPath, cchPath, pszExt)
; pszPath : LPWSTR in/out -> "var"
; cchPath : UINT_PTR -> "intptr"
; pszExt : LPCWSTR -> "wstr"
; ※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 (
	api_ms_win_core_path_l1_1_0 = windows.NewLazySystemDLL("api-ms-win-core-path-l1-1-0.dll")
	procPathCchAddExtension = api_ms_win_core_path_l1_1_0.NewProc("PathCchAddExtension")
)

// pszPath (LPWSTR in/out), cchPath (UINT_PTR), pszExt (LPCWSTR)
r1, _, err := procPathCchAddExtension.Call(
	uintptr(pszPath),
	uintptr(cchPath),
	uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(pszExt))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // HRESULT

function PathCchAddExtension(
  pszPath: PWideChar;   // LPWSTR in/out
  cchPath: NativeUInt;   // UINT_PTR
  pszExt: PWideChar   // LPCWSTR
): Integer; stdcall;
  external 'api-ms-win-core-path-l1-1-0.dll' name 'PathCchAddExtension';

result := DllCall("api-ms-win-core-path-l1-1-0\PathCchAddExtension"
    , "Ptr", pszPath   ; LPWSTR in/out
    , "UPtr", cchPath   ; UINT_PTR
    , "WStr", pszExt   ; LPCWSTR
    , "Int")   ; return: HRESULT

●PathCchAddExtension(pszPath, cchPath, pszExt) = DLL("api-ms-win-core-path-l1-1-0.dll", "int PathCchAddExtension(char*, int, char*)")
# 呼び出し: PathCchAddExtension(pszPath, cchPath, pszExt)
# pszPath : LPWSTR in/out -> "char*"
# cchPath : UINT_PTR -> "int"
# pszExt : 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)。