PathFindExtensionW

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

LPWSTR PathFindExtensionW(
    LPCWSTR pszPath
);

<DllImport("SHLWAPI.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function PathFindExtensionW(
    <MarshalAs(UnmanagedType.LPWStr)> pszPath As String   ' LPCWSTR
) As IntPtr
End Function

' pszPath : LPCWSTR
Declare PtrSafe Function PathFindExtensionW Lib "shlwapi" ( _
    ByVal pszPath As LongPtr) As LongPtr
' 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

PathFindExtensionW = ctypes.windll.shlwapi.PathFindExtensionW
PathFindExtensionW.restype = wintypes.LPWSTR
PathFindExtensionW.argtypes = [
    wintypes.LPCWSTR,  # pszPath : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

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

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

$sig = @"
[DllImport("SHLWAPI.dll", CharSet = CharSet.Unicode)]
public static extern IntPtr PathFindExtensionW([MarshalAs(UnmanagedType.LPWStr)] string pszPath);
"@
$api = Add-Type -MemberDefinition $sig -Name 'SHLWAPI_PathFindExtensionW' -Namespace Win32 -PassThru
# $api::PathFindExtensionW(pszPath)

#uselib "SHLWAPI.dll"
#func global PathFindExtensionW "PathFindExtensionW" wptr
; PathFindExtensionW pszPath   ; 戻り値は stat
; pszPath : 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 "SHLWAPI.dll"
#cfunc global PathFindExtensionW "PathFindExtensionW" wstr
; res = PathFindExtensionW(pszPath)
; pszPath : LPCWSTR -> "wstr"

; LPWSTR PathFindExtensionW(LPCWSTR pszPath)
#uselib "SHLWAPI.dll"
#cfunc global PathFindExtensionW "PathFindExtensionW" wstr
; res = PathFindExtensionW(pszPath)
; pszPath : LPCWSTR -> "wstr"

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

var (
	shlwapi = windows.NewLazySystemDLL("SHLWAPI.dll")
	procPathFindExtensionW = shlwapi.NewProc("PathFindExtensionW")
)

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

function PathFindExtensionW(
  pszPath: PWideChar   // LPCWSTR
): PWideChar; stdcall;
  external 'SHLWAPI.dll' name 'PathFindExtensionW';

result := DllCall("SHLWAPI\PathFindExtensionW"
    , "WStr", pszPath   ; LPCWSTR
    , "Ptr")   ; return: LPWSTR

●PathFindExtensionW(pszPath) = DLL("SHLWAPI.dll", "char* PathFindExtensionW(char*)")
# 呼び出し: PathFindExtensionW(pszPath)
# pszPath : 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。