ucnv_setSubstChars

// icuuc.dll
#include <windows.h>

void ucnv_setSubstChars(
    UConverter* converter,
    LPCSTR subChars,
    CHAR len,
    UErrorCode* err
);

<DllImport("icuuc.dll", ExactSpelling:=True, CallingConvention:=CallingConvention.Cdecl)>
Public Shared Sub ucnv_setSubstChars(
    ByRef converter As IntPtr,   ' UConverter* in/out
    <MarshalAs(UnmanagedType.LPStr)> subChars As String,   ' LPCSTR
    len As SByte,   ' CHAR
    ByRef err As Integer   ' UErrorCode* in/out
)
End Sub

' converter : UConverter* in/out
' subChars : LPCSTR
' len : CHAR
' err : UErrorCode* in/out
Declare PtrSafe Sub ucnv_setSubstChars Lib "icuuc" ( _
    ByRef converter As LongPtr, _
    ByVal subChars As String, _
    ByVal len As Byte, _
    ByRef err As Long)
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

ucnv_setSubstChars = ctypes.cdll.icuuc.ucnv_setSubstChars
ucnv_setSubstChars.restype = None
ucnv_setSubstChars.argtypes = [
    ctypes.c_void_p,  # converter : UConverter* in/out
    wintypes.LPCSTR,  # subChars : LPCSTR
    ctypes.c_byte,  # len : CHAR
    ctypes.c_void_p,  # err : UErrorCode* in/out
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('icuuc.dll')
ucnv_setSubstChars = Fiddle::Function.new(
  lib['ucnv_setSubstChars'],
  [
    Fiddle::TYPE_VOIDP,  # converter : UConverter* in/out
    Fiddle::TYPE_VOIDP,  # subChars : LPCSTR
    Fiddle::TYPE_CHAR,  # len : CHAR
    Fiddle::TYPE_VOIDP,  # err : UErrorCode* in/out
  ],
  Fiddle::TYPE_VOID, Fiddle::Function::CDECL)

#[link(name = "icuuc")]
extern "C" {
    fn ucnv_setSubstChars(
        converter: *mut isize,  // UConverter* in/out
        subChars: *const u8,  // LPCSTR
        len: i8,  // CHAR
        err: *mut i32  // UErrorCode* in/out
    );
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("icuuc.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern void ucnv_setSubstChars(ref IntPtr converter, [MarshalAs(UnmanagedType.LPStr)] string subChars, sbyte len, ref int err);
"@
$api = Add-Type -MemberDefinition $sig -Name 'icuuc_ucnv_setSubstChars' -Namespace Win32 -PassThru
# $api::ucnv_setSubstChars(converter, subChars, len, err)

#uselib "icuuc.dll"
#func global ucnv_setSubstChars "ucnv_setSubstChars" sptr, sptr, sptr, sptr
; ucnv_setSubstChars converter, subChars, len, err
; converter : UConverter* in/out -> "sptr"
; subChars : LPCSTR -> "sptr"
; len : CHAR -> "sptr"
; err : UErrorCode* in/out -> "sptr"

#uselib "icuuc.dll"
#func global ucnv_setSubstChars "ucnv_setSubstChars" int, str, int, int
; ucnv_setSubstChars converter, subChars, len, err
; converter : UConverter* in/out -> "int"
; subChars : LPCSTR -> "str"
; len : CHAR -> "int"
; err : UErrorCode* in/out -> "int"

; void ucnv_setSubstChars(UConverter* converter, LPCSTR subChars, CHAR len, UErrorCode* err)
#uselib "icuuc.dll"
#func global ucnv_setSubstChars "ucnv_setSubstChars" int, str, int, int
; ucnv_setSubstChars converter, subChars, len, err
; converter : UConverter* in/out -> "int"
; subChars : LPCSTR -> "str"
; len : CHAR -> "int"
; err : UErrorCode* in/out -> "int"

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

var (
	icuuc = windows.NewLazySystemDLL("icuuc.dll")
	procucnv_setSubstChars = icuuc.NewProc("ucnv_setSubstChars")
)

// converter (UConverter* in/out), subChars (LPCSTR), len (CHAR), err (UErrorCode* in/out)
r1, _, err := procucnv_setSubstChars.Call(
	uintptr(converter),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(subChars))),
	uintptr(len),
	uintptr(err),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // void

procedure ucnv_setSubstChars(
  converter: Pointer;   // UConverter* in/out
  subChars: PAnsiChar;   // LPCSTR
  len: Shortint;   // CHAR
  err: Pointer   // UErrorCode* in/out
); cdecl;
  external 'icuuc.dll' name 'ucnv_setSubstChars';

result := DllCall("icuuc\ucnv_setSubstChars"
    , "Ptr", converter   ; UConverter* in/out
    , "AStr", subChars   ; LPCSTR
    , "Char", len   ; CHAR
    , "Ptr", err   ; UErrorCode* in/out
    , "Cdecl Int")   ; return: void

●ucnv_setSubstChars(converter, subChars, len, err) = DLL("icuuc.dll", "int ucnv_setSubstChars(void*, char*, char, void*)")
# 呼び出し: ucnv_setSubstChars(converter, subChars, len, err)
# converter : UConverter* in/out -> "void*"
# subChars : LPCSTR -> "char*"
# len : CHAR -> "char"
# err : UErrorCode* in/out -> "void*"
# 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)。
# ※cdecl関数。DLL()宣言はstdcall前提。cdeclは EXEC_PTR(`cdecl`,…) を使用。