小编alt*_*raz的帖子

我像往常一样经历了MSDN上的所有漫步,它们毫无价值 - 非常有限.

如果我在我的类中使内部对象成为单个类,我可以显示信息,但是只要将其转换为对象列表(集合),我就会在显示中得到#Error.

这是一个更新的例子.

举个例子,我有一个Person对象,可以有一个或多个电话号码(号码列表),我找不到办法来访问电话号码.

[Serializable]
public class Person
{
    private readonly List<PhoneNumber> _numbers = new List<PhoneNumber>();

    public Person()
    {
    }

    public Person(int id, string name, string address, decimal salary)
    {
        Id = id;
        Name = name;
        Address = address;
        Salary = salary;
    }

    public void AddNumber(PhoneNumber number)
    {
        _numbers.Add(number);            
    }


    public int Id { get; set; }
    public string Name { get; set; }
    public string Address { get; set; }

    public List<PhoneNumber> PhoneNumbers { get { return …

我正在画一个带笔的曲线形状.

我需要在图形中填充颜色,我该怎么做？

这是我的代码:

Pen p1 = new Pen(Color.Red);
Graphics g1 = panel1.CreateGraphics();
g1.DrawCurve(p1, new Point[] { new Point(470, 470), new Point(430, 440), new Point(400, 480), new Point(470, 560), });
Graphics g2 = panel1.CreateGraphics();
g2.DrawCurve(p1, new Point[] { new Point(470, 470), new Point(510, 440), new Point(540, 480), new Point(470, 560), });

我找到了填充路径,但我不知道如何使用它.

为了运行executeScalar,我在互联网上尝试了很多建议,但是我得到了错误ExecuteScalar: Connection property has not been initialized.我的INSERT查询工作正常,问题在于executeScalar.

conn.Open();
SqlCommand cmd = new SqlCommand(
    "INSERT INTO Products (Product_Name,Product_BarCode,Product_CP,Product_SP,
                           Product_Countainer,Product_Pcs,Product_MFGDate,
                           Product_ExpiryDate,Product_Grade)
     Values ('" + Name.Text + "','" + BarCode.Text + "','" + CostP.Value + "','" + 
             SellingP.Value + "','" + Countainer.Value + "','" + Pcs.Value + "','" + 
             MfgDate.Value + "','" + ExpDate.Value + "','" + Grade.SelectedItem + "')", 
     conn);
cmd.ExecuteNonQuery();
conn.Close();

conn.Open();
cmd.Connection = conn;
cmd = new SqlCommand("Select SUM(Product_CP) From Products AS …