C++实现编码转换的示例代码

// convert.h
/*
 * @Author: gongluck 
 * @Date: 2020-03-23 16:06:23 
 * @Last Modified by: gongluck
 * @Last Modified time: 2020-03-23 16:09:30
 */

// Character encoding conversion

#pragma once

#include <string>

namespace gconvert
{
// ANSI->Unicode
int ansi2uni(const std::string& ansi, std::wstring& uni);

// Unicode->ANSI
int uni2ansi(const std::wstring& uni, std::string& ansi);

// UTF8->Unicode
int utf82uni(const std::string& utf8, std::wstring& uni);

// Unicode->UTF8
int uni2utf8(const std::wstring& uni, std::string& utf8);

// ANSI->UTF8
int ansi2utf8(const std::string& ansi, std::string& utf8);

// UTF8->ANSI
int utf82ansi(const std::string& utf8, std::string& ansi);
} // namespace gconvert

//convert.cpp
/*
 * @Author: gongluck 
 * @Date: 2020-03-23 16:13:01 
 * @Last Modified by: gongluck
 * @Last Modified time: 2020-03-23 16:34:50
 */

#include "convert.h"

#include <iostream>

#ifdef _WIN32
#include <windows.h>
#endif

namespace gconvert
{
#ifdef _WIN32
 static int multi2uni(const std::string& multi, std::wstring& uni, UINT code)
 {
  auto len = MultiByteToWideChar(code, 0, multi.c_str(), -1, nullptr, 0);
  if (len <= 0)
  {
   std::cerr << __FILE__ << " : " << __LINE__ << " : " << GetLastError() << std::endl;
   return -1;
  }
  WCHAR* buf = new WCHAR[len];
  if (buf == nullptr)
  {
   std::cerr << __FILE__ << " : " << __LINE__ << " : " << "can not new buf, size : " << len << std::endl;
   return -2;
  }
  len = MultiByteToWideChar(code, 0, multi.c_str(), -1, buf, len);
  uni.assign(buf);
  delete[]buf;
  buf = nullptr;
  return len;
 }

 static int uni2multi(const std::wstring& uni, std::string& multi, UINT code)
 {
  auto len = WideCharToMultiByte(code, 0, uni.c_str(), -1, nullptr, 0, nullptr, nullptr);
  if (len <= 0)
  {
   std::cerr << __FILE__ << " : " << __LINE__ << " : " << GetLastError() << std::endl;
   return -1;
  }
  CHAR* buf = new CHAR[len];
  if (buf == nullptr)
  {
   std::cerr << __FILE__ << " : " << __LINE__ << " : " << "can not new buf, size : " << len << std::endl;
   return -2;
  }
  len = WideCharToMultiByte(code, 0, uni.c_str(), -1, buf, len, nullptr, nullptr);
  multi.assign(buf);
  delete[]buf;
  buf = nullptr;
  return len;
 }
#endif

// ANSI->Unicode
int ansi2uni(const std::string& ansi, std::wstring& uni)
{
#ifdef _WIN32
 return multi2uni(ansi, uni, CP_ACP);
#endif
 return 0;
}

// Unicode->ANSI
int uni2ansi(const std::wstring &uni, std::string &ansi)
{
#ifdef _WIN32
 return uni2multi(uni, ansi, CP_ACP);
#endif
 return 0;
}

// UTF8->Unicode
int utf82uni(const std::string& utf8, std::wstring& uni)
{
#ifdef _WIN32
 return multi2uni(utf8, uni, CP_UTF8);
#endif
 return 0;
}

// Unicode->UTF8
int uni2utf8(const std::wstring& uni, std::string& utf8)
{
#ifdef _WIN32
 return uni2multi(uni, utf8, CP_UTF8);
#endif
 return 0;
}

// ANSI->UTF8
int ansi2utf8(const std::string &ansi, std::string &utf8)
{
 std::wstring uni;
 auto len = ansi2uni(ansi, uni);
 if (len <= 0)
 {
  return -3;
 }
 return uni2utf8(uni, utf8);
}

// UTF8->ANSI
int utf82ansi(const std::string &utf8, std::string &ansi)
{
 std::wstring uni;
 auto len = utf82uni(utf8, uni);
 if (len <= 0)
 {
  return -3;
 }
 return uni2ansi(uni, ansi);
}
} // namespace gconvert

//testcode
#include <iostream>

#include "../code conversion/convert.h"

int main()
{
 std::string ansi = "你好，世界！";
 std::wstring uni;
 std::string utf8;
 ret = gconvert::ansi2uni(ansi, uni);
 ret = gconvert::ansi2utf8(ansi, utf8);
 ret = gconvert::uni2ansi(uni, ansi);
 ret = gconvert::uni2utf8(uni, utf8);
 ret = gconvert::utf82ansi(utf8, ansi);
 ret = gconvert::utf82uni(utf8, uni);
 return 0;
}