Introduction to ASP. NET User Controls

Access the data in the user control on the page:

Method 1:
Use the FindControl method of the user control to find the control in the user control and obtain its data (you do not need to process it in the control, but you need to know the ID of the control to be used in the user control)
Method 2:

Add a property (method) for the control and use this property to access data in the user control (it is easy to use in the target page, but not flexible enough)

Access the control in the page control in the user control:

Method 1:
Use the Parent property in the user control to find the page, and then use the FindControl method to find the control to access

Method 2:
Add events to the user control, process events on the page, and access the control on the page.