Using a nullable boolean.

It is possible to assign a nullable boolean in C#. The trick is to use ? in the declaration. Once declared, one can use the HasValue() method. An example follows:

    protected void Page_Load(object sender, EventArgs e)
    {
        bool? isUser = null;
        lblStatus.Text = isUser.HasValue.ToString(); //displays false
        // an int example: Nullable<int> i = null;
    }
    protected void btnCheckStatus_Click(object sender, EventArgs e)
    {
        bool? isUser = false;
        lblStatus.Text = isUser.HasValue.ToString(); //displays true
    }