If (! Ispostback) usage?

1. ispostback explanation: gets a value indicating whether the page is being loaded in response to the client's sending back, or whether the page is being loaded and accessed for the first time, if the page is loaded in response to the client sending back, it is true; otherwise, it is false. For example, if you press the button on the page, you will see that ispostback is equal to true during page_load; if your page is opened for the first time, false is returned ;! This. ispostback is always true, and the content on this page is always regarded as the first time to open.
Ii. Usage:

If (! This. ispostback)
{

// Todo: Put the page initialization code.

}

Iii. Summary:

1 ,! The code in ispostback indicates what to do when the page is opened for the first time.Initialization.

2, if (! This. ispostback) code is only executed once. If the page is refreshed again, this statement is not executed.