How to add an event into user control in ASP.NET WebForms?

Reason: Put two user controls in same page, you want call one function in B while one thing happens in A.

Three steps to do that: Define, Raise and Book event. 

Define event in A:

    public delegate void AfterOneTask ();

    public event AfterOneTask AfterOneTaskHandler;

Raise event in A:

    protected void Submit_Click(object sender, EventArgs e)

    {

       ….

        if (this. AfterOneTaskHandler!= null) AfterOneTaskHandler();

       }

Book event in B:

    protected void Page_Init(object sender, EventArgs e)

    {

        this.ctlA.AfterOneTaskHandler +=new UserControlA.AfterOneTask(controlb.method1);

    }