public InputCourseForm(Course c)
        {//c非空为修改窗体;否则为增加窗体
            InitializeComponent();
            if (c == null)
            {
                tbCourseNo.Enabled = true;
                this.Text          = "增加课程";
                isUpdate           = false;
                btnAdd.Text        = "增加";
            }
            else
            {
                this.Text          = "修改课程信息";
                tbCourseNo.Enabled = false;

                tbCourseNo.Text   = c.courseNo;
                tbCourseName.Text = c.courseName;
                tbPoint.Text      = c.point.ToString("0.0");
                isUpdate          = true;
                btnAdd.Text       = "保存修改";
                dept = CourseManageAction.getDept(c);
            }
        }