C++ – Windows下字符串UTF8编码转ANSI，ANSI转UTF8编码

1 Windows下字符串UTF8与ANSI编码相互转换

1.1 UTF8转ANSI

#include <Windows.h>

std::string UTF8ToAnsi(const std::string& str)
{
    int nwLen = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, NULL, 0);
    wchar_t* pwBuf = new wchar_t[nwLen + 1];//一定要加1，不然会出现尾巴
    memset(pwBuf, 0, nwLen * 2 + 2);
    MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.length(), pwBuf, nwLen);
    int nLen = WideCharToMultiByte(CP_ACP, 0, pwBuf, -1, NULL, NULL, NULL, NULL);
    char* pBuf = new char[nLen + 1];
    memset(pBuf, 0, nLen + 1);
    WideCharToMultiByte(CP_ACP, 0, pwBuf, nwLen, pBuf, nLen, NULL, NULL);
    std::string retStr = pBuf;
    delete[]pBuf;
    delete[]pwBuf;
    pBuf = NULL;
    pwBuf = NULL;
    return retStr;
}

1.2 ANSI转UTF8

std::string AnsiToUTF8(const std::string& str)
{
    int nwLen = ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, NULL, 0);
    wchar_t* pwBuf = new wchar_t[nwLen + 1];//一定要加1，不然会出现尾巴
    ZeroMemory(pwBuf, nwLen * 2 + 2);
    ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), pwBuf, nwLen);
    int nLen = ::WideCharToMultiByte(CP_UTF8, 0, pwBuf, -1, NULL, NULL, NULL, NULL);
    char* pBuf = new char[nLen + 1];
    ZeroMemory(pBuf, nLen + 1);
    ::WideCharToMultiByte(CP_UTF8, 0, pwBuf, nwLen, pBuf, nLen, NULL, NULL);
    std::string retStr(pBuf);
    delete[]pwBuf;
    delete[]pBuf;
    pwBuf = NULL;
    pBuf = NULL;
    return retStr;
}

1.3 相互转换示例

#include <iostream>
#include <Windows.h>

std::string UTF8ToAnsi(const std::string& str)
{
    int nwLen = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, NULL, 0);
    wchar_t* pwBuf = new wchar_t[nwLen + 1];//一定要加1，不然会出现尾巴
    memset(pwBuf, 0, nwLen * 2 + 2);
    MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.length(), pwBuf, nwLen);
    int nLen = WideCharToMultiByte(CP_ACP, 0, pwBuf, -1, NULL, NULL, NULL, NULL);
    char* pBuf = new char[nLen + 1];
    memset(pBuf, 0, nLen + 1);
    WideCharToMultiByte(CP_ACP, 0, pwBuf, nwLen, pBuf, nLen, NULL, NULL);
    std::string retStr = pBuf;
    delete[]pBuf;
    delete[]pwBuf;
    pBuf = NULL;
    pwBuf = NULL;
    return retStr;
}

std::string AnsiToUTF8(const std::string& str)
{
    int nwLen = ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, NULL, 0);
    wchar_t* pwBuf = new wchar_t[nwLen + 1];//一定要加1，不然会出现尾巴
    ZeroMemory(pwBuf, nwLen * 2 + 2);
    ::MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), pwBuf, nwLen);
    int nLen = ::WideCharToMultiByte(CP_UTF8, 0, pwBuf, -1, NULL, NULL, NULL, NULL);
    char* pBuf = new char[nLen + 1];
    ZeroMemory(pBuf, nLen + 1);
    ::WideCharToMultiByte(CP_UTF8, 0, pwBuf, nwLen, pBuf, nLen, NULL, NULL);
    std::string retStr(pBuf);
    delete[]pwBuf;
    delete[]pBuf;
    pwBuf = NULL;
    pBuf = NULL;
    return retStr;
}

int main()
{
    std::string u8_str = u8"E:\\新建文件夹\\破晓的博客";

    std::string ansi_str = UTF8ToAnsi(u8_str);

    std::string u8_convert = AnsiToUTF8(ansi_str);

    if (u8_convert.compare(u8_str) == 0)
    {
        std::cout << "UTF8字符串转换前与转换后结果一致" << std::endl;
    }

    return 0;
}