C++：编码转换

1.GBK转UTF-8（解码），这方法包含两部分：DecodeUtf8fromString函数和WString2String函数--windows环境

std::string WString2String(std::wstring &in)
{
    int nLen = WideCharToMultiByte(CP_ACP, 0, in.c_str(), -1, NULL, 0, NULL, NULL);
    if (nLen <= 0) return std::string("");
    char* pszDst = new char[nLen];
    if (NULL == pszDst) return std::string("");
    WideCharToMultiByte(CP_ACP, 0, in.c_str(), -1, pszDst, nLen, NULL, NULL);
    pszDst[nLen - 1] = 0;
    std::string strTemp(pszDst);
    delete[] pszDst;
    return strTemp;
}
//解码
std::string  DecodeUtf8fromString(std::string in)
{
    int  len = 0;
    len = in.length();
    int  unicodeLen = ::MultiByteToWideChar(CP_UTF8, 0, in.c_str(), -1, NULL, 0);
    wchar_t *  pUnicode;
    pUnicode = new  wchar_t[unicodeLen + 1];
    memset(pUnicode, 0, (unicodeLen + 1)*sizeof(wchar_t));
    ::MultiByteToWideChar(CP_UTF8, 0, in.c_str(), -1, (LPWSTR)pUnicode, unicodeLen);
    std::wstring  rt;
    rt = (wchar_t*)pUnicode;
    delete  pUnicode;
    return WString2String(rt);
}
 

2.转码 其他编码转UTF-8，此方法包含两部分：EncodeUtf8fromString和EncodeUtf8fromWstring函数--windows环境

std::string EncodeUtf8fromWstring(std::wstring in)
{
    std::string s(in.length() * 3 + 1, ' ');
    size_t len = ::WideCharToMultiByte(CP_UTF8, 0,
        in.c_str(), in.length(),
        &s[0], s.length(),
        NULL, NULL);
    s.resize(len);
    return s;
}
//（gbk）字符串转utf8---转码
std::string EncodeUtf8fromString(std::string in)
{
    std::wstring wszStr;
    int nLength = MultiByteToWideChar(CP_ACP, 0, in.c_str(), -1, NULL, NULL);
    wszStr.resize(nLength);

    LPWSTR lpwszStr = new wchar_t[nLength];
    MultiByteToWideChar(CP_ACP, 0, in.c_str(), -1, lpwszStr, nLength);
    wszStr = lpwszStr;

    delete[] lpwszStr;

    return EncodeUtf8fromWstring(wszStr);
}