lstrlenW

// KERNEL32.dll  (Unicode / -W)
#include <windows.h>

INT lstrlenW(
    LPCWSTR lpString
);

<DllImport("KERNEL32.dll", CharSet:=CharSet.Unicode, ExactSpelling:=True)>
Public Shared Function lstrlenW(
    <MarshalAs(UnmanagedType.LPWStr)> lpString As String   ' LPCWSTR
) As Integer
End Function

' lpString : LPCWSTR
Declare PtrSafe Function lstrlenW Lib "kernel32" ( _
    ByVal lpString 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

lstrlenW = ctypes.windll.kernel32.lstrlenW
lstrlenW.restype = ctypes.c_int
lstrlenW.argtypes = [
    wintypes.LPCWSTR,  # lpString : LPCWSTR
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('KERNEL32.dll')
lstrlenW = Fiddle::Function.new(
  lib['lstrlenW'],
  [
    Fiddle::TYPE_VOIDP,  # lpString : LPCWSTR
  ],
  Fiddle::TYPE_INT)
# Wide strings: pass str.encode("UTF-16LE") + "\x00\x00"

#[link(name = "kernel32")]
extern "system" {
    fn lstrlenW(
        lpString: *const u16  // LPCWSTR
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("KERNEL32.dll", CharSet = CharSet.Unicode)]
public static extern int lstrlenW([MarshalAs(UnmanagedType.LPWStr)] string lpString);
"@
$api = Add-Type -MemberDefinition $sig -Name 'KERNEL32_lstrlenW' -Namespace Win32 -PassThru
# $api::lstrlenW(lpString)

#uselib "KERNEL32.dll"
#func global lstrlenW "lstrlenW" wptr
; lstrlenW lpString   ; 戻り値は stat
; lpString : 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 "KERNEL32.dll"
#cfunc global lstrlenW "lstrlenW" wstr
; res = lstrlenW(lpString)
; lpString : LPCWSTR -> "wstr"

; INT lstrlenW(LPCWSTR lpString)
#uselib "KERNEL32.dll"
#cfunc global lstrlenW "lstrlenW" wstr
; res = lstrlenW(lpString)
; lpString : LPCWSTR -> "wstr"

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

var (
	kernel32 = windows.NewLazySystemDLL("KERNEL32.dll")
	proclstrlenW = kernel32.NewProc("lstrlenW")
)

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

function lstrlenW(
  lpString: PWideChar   // LPCWSTR
): Integer; stdcall;
  external 'KERNEL32.dll' name 'lstrlenW';

result := DllCall("KERNEL32\lstrlenW"
    , "WStr", lpString   ; LPCWSTR
    , "Int")   ; return: INT

●lstrlenW(lpString) = DLL("KERNEL32.dll", "int lstrlenW(char*)")
# 呼び出し: lstrlenW(lpString)
# lpString : 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。