GetUserNameEx() problem

// Description:
//   Function gets user name.
void CollectUserName() {
    // Name format, we need the longest, most descriptive one.
    EXTENDED_NAME_FORMAT name_format = NameSamCompatible;

    // Local memory pointer to store user name.
    TCHAR *user_name = NULL;

    // This will hold user_name size in TCHARs on input and required size
    // of user_name on output.
    ULONG user_name_size = 1;

    ULONG required_size;

    // Will give GetUserNameEx() minimal buffer. Not sure if it will accept
    // 0-length buffer (this case is not documented).
    user_name = new (nothrow) TCHAR[1];

    HRESULT result = GetUserNameEx(name_format, user_name, &user_name_size);

    required_size = user_name_size;

    delete [] user_name;

    user_name = NULL;

    // Allocating block of memory of the required size.
    user_name = new (nothrow) TCHAR[user_name_size];

    result = GetUserNameEx(name_format, user_name, &user_name_size);

    cout << required_size << user_name_size;
    // Output: 22 11 - for Character Encoding set to "Not Set"
    //         11 11 - for Character Encoding set to "Use Unicode Chracter Set"
}