相关疑难解决方法(0)

我很难理解这一点.请考虑以下示例:

protected void Page_Load(object sender, EventArgs e)
{
    // No surprise that this works
    Int16 firstTest = Convert.ToInt16(0);
    int firstTest2 = (int)firstTest;

    // This also works
    object secondTest = 0;
    int secondTest2 = (int)secondTest;

    // But this fails!
    object thirdTest = Convert.ToInt16(0);
    int thirdtest2 = (int)thirdTest;  // It blows up on this line.
}

我在运行时获得的具体错误是在Visual Studio中的Specified cast is not valid. If I QuickWatch (int)thirdTest,我得到的值为Cannot unbox 'thirdTest' as a 'int'.

到底发生了什么事？