Ispostback Property and Pointer Use

Question

Hi What is Ispostback Property in ASP.Net. Why do we use that. How can we use pointers in ASP.Net ?

MuthuMari M · Answer

Hi, Ispostback : Gets a value that indicates whether the page is being rendered for the first time or is being loaded in response to a postback. The following example shows how to test the value of the IsPostBack property when the page is loaded in order to determine whether the page is being rendered for the first time or is responding to a postback. If the page is being rendered for the first time, the code calls the Page.Validate method. private void Page_Load() { if (!IsPostBack) { // Validate initially to force asterisks // to appear before the first roundtrip. Validate(); } } Pointers : Pointers are variables that hold the addresses of other variables. For example, if x contains the address of y, then x is said to "point to" y. Once a pointer points to a variable, the value of that variable can be obtained or changed through the pointer. type* var-name; thanks. If this post is useful then mark it as " Accepted Answer "

Satyapriya Nayak · Answer

Hi Arun, IsPostBack property indicates that whether this is the first time user has requested fort the page or it is reloaded based on any response on postback. This property checks for __VIEWSTATE or __EVENTTARGET parameter in Request object. if these parameters are absent that means it is requested for the first time and if these parameters are present then this request is not first request. The page exposes the IsPostBack property. This is a read-only Boolean property that indicates if the page or control is being loaded for the first time, or if it is being loaded in response to a client postback. Many expensive operations (such as getting data from a database or populating ListItems) must be performed only the first time the page or control is loaded. If the page is posted to the server and then reloaded, there is no need to repeat the operation Example 1. Testing for IsPostBack in VB.NET sub Page_Load(ByVal Sender as Object, _ ByVal e as EventArgs) if not IsPostBack then ' Do the expensive operations only the ' first time the page is loaded. end if end sub Example 2. Testing for IsPostBack in C# void Page_Load(Object sender, EventArgs e) { if (! IsPostBack) { // Do the expensive operations only the // first time the page is loaded. } } Thanks

Ispostback Property and Pointer Use

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