C++ std::wstring 互转 std::string

1、std::wstring 转 std::string

string WstringToString(const std::wstring wstr)
{
#if 1
    std::string result;
    int len = WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), NULL, 0, NULL, NULL);
    if( len <= 0 )
        return result;
 
    char* buffer = new char[len + 1];
    if(buffer == NULL )
        return result;
 
    WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), wstr.size(), buffer, len, NULL, NULL);
    buffer[len] = '\0';
    result.append(buffer);
    delete[] buffer;
 
    return result;
#else
    //unsigned len = (unsigned)str.size() * 4;
    setlocale(LC_CTYPE, "");
    //char *p = new char[len];
    //wcstombs(p,str.c_str(),len);
    //std::string str1(p);
    //delete[] p;
    //return str1;
#endif
}

2、std::string 转 std::wstring

wstring StringToWString(const string str) 
{
    //int num = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, NULL, 0);
    //wchar_t *wide = new wchar_t[num];
    //MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, wide, num);
    //std::wstring w_str(wide);
    //delete[] wide;
    //return w_str;
 
    wstring result;  
    //获取缓冲区大小，并申请空间，缓冲区大小按字符计算  
    int len = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), NULL, 0);  
    TCHAR* buffer = new TCHAR[len + 1];  
    //多字节编码转换成宽字节编码  
    MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.size(), buffer, len);  
    buffer[len] = '\0';             //添加字符串结尾  
    //删除缓冲区并返回值  
    result.append(buffer);  
    delete[] buffer;  
    return result;
 
}