C# 如何在C中创建属性更改事件和更改事件#

我创建了一个属性

public int PK_ButtonNo 
{
    get { return PK_ButtonNo; }
    set { PK_ButtonNo = value; }
}

现在，我想将事件添加到此属性，以进行值更改和更改

我写了两个事件。在这里，我希望两个事件都包含更改的值和更改的值

i、 e

当用户实现事件时。他必须拥有

e.OldValue

，

e.NewValue

public event EventHandler ButtonNumberChanging;
public event EventHandler ButtonNumberChanged;

public int PK_ButtonNo 
{
    get { return PK_ButtonNo; }
    private set
    {
        if (PK_ButtonNo == value)
            return;

        if (ButtonNumberChanging != null)
            this.ButtonNumberChanging(this,null);

        PK_ButtonNo = value;

        if (ButtonNumberChanged != null)
            this.ButtonNumberChanged(this,null);
    }
}

---

实施此事件时，我将如何获取更改值和更改值。

将以下类添加到项目中：

public class ValueChangingEventArgs : EventArgs
{
    public int OldValue{get;private set;}
    public int NewValue{get;private set;}

    public bool Cancel{get;set;}

    public ValueChangingEventArgs(int OldValue, int NewValue)
    {
        this.OldValue = OldValue;
        this.NewValue = NewValue;
        this.Cancel = false;
    }
}

现在，在类中添加更改事件声明：

public EventHandler<ValueChangingEventArgs> ButtonNumberChanging;

和财产：

public int PK_ButtonNo
{
    get{ return this.m_pkButtonNo; }
    private set
    {
        if (ButtonNumberChanging != null)

        ValueChangingEventArgs vcea = new ValueChangingEventArgs(PK_ButtonNo, value);
        this.ButtonNumberChanging(this, vcea);

        if (!vcea.Cancel)
        {
            this.m_pkButtonNo = value;

            if (ButtonNumberChanged != null)
            this.ButtonNumberChanged(this,EventArgs.Empty);
        }
    }
}

---

“Cancel”属性允许用户取消更改操作，这是x-ing事件中的标准，例如“FormClosing”、“Validating”等。

发布它！让更好的解决方案获胜！（：@Nathan:是的，你能做到。谢谢Nissim和所有努力提供解决方案的人。@Shantanu我并不担心，Nissim的解决方案是一模一样的。你在叫“PK_ButtonNo”内部！这将导致StackOverflow异常。添加一个私有成员并让属性访问itOk Nissim：我没有注意到。谢谢

public int PK_ButtonNo
{
    get{ return this.m_pkButtonNo; }
    private set
    {
        if (ButtonNumberChanging != null)

        ValueChangingEventArgs vcea = new ValueChangingEventArgs(PK_ButtonNo, value);
        this.ButtonNumberChanging(this, vcea);

        if (!vcea.Cancel)
        {
            this.m_pkButtonNo = value;

            if (ButtonNumberChanged != null)
            this.ButtonNumberChanged(this,EventArgs.Empty);
        }
    }
}