convert Shift-JIS string to utf-8 on Visual C++ (Microsoft Visual Studio Express 2013 for Windows Desktop)

sjis2utf8.cpp

#include "stdafx.h"
#include <string>

//VC++ SJIS string を utf-8のstringに変換する
string sjis2utf8(const string& sjis) {
	string utf8_string;

	//一旦SJISからutf-16へ変換
	LPCCH pSJIS = (LPCCH)sjis.c_str();
	int utf16size = ::MultiByteToWideChar(CP_ACP, MB_ERR_INVALID_CHARS, pSJIS, -1, 0, 0);
	if (utf16size != 0) {
		LPWSTR pUTF16 = new WCHAR[utf16size];
		if (::MultiByteToWideChar(CP_ACP, 0, (LPCCH)pSJIS, -1, pUTF16, utf16size) != 0) {
			//次にutf-16からutf-8へ変換
			int utf8size = ::WideCharToMultiByte(CP_UTF8, 0, pUTF16, -1, 0, 0, 0, 0);
			if (utf8size != 0) {
				LPTSTR pUTF8 = new TCHAR[utf8size + 16];
				ZeroMemory(pUTF8, utf8size + 16);
				if (::WideCharToMultiByte(CP_UTF8, 0, pUTF16, -1, pUTF8, utf8size, 0, 0) != 0) {
					utf8_string = string(pUTF8);
				}
				delete pUTF8;
			}
		}
		delete pUTF16;
	}
	return utf8_string;
}

It'll be better replace CP_ACP as 932.
because if your host windows not japanese charset but chinese, CP_ACP is ANSI default, the convertion will failed.

https://docs.microsoft.com/en-us/windows/win32/intl/code-page-identifiers