Method to modify the value of the master page control on the page page after referencing the master page

The specific conditions are as follows:
1. First, the page must refer to the master page to be modified;
2. On the page page, create a strongly typed reference to the master page by setting the page directive @MasterType, and specify the virtual path to generate the strongly typed file, for example:

<%@ MasterType VirtualPath="~/Demo.Master" %>

3. Add an public property to the master page and assign the set value to the master page control, for example:

　　　　public string PageTitle
        {
            set {
                this.LabPageTitle.Text = value;
            }
        }

After the above conditions are met, you can modify the value of the control above the master page on the page page, for example:

　　　　protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.Master.PageTitle = "Page Page modifies the value of the master page control ";
            }
        }

The LabTitle control value on the Master page is then set to "Page page modifies the master page control value.