what is Viewstate in ASP.NET with example.

View State can be used to store state information for a single user. View State is a built in feature in web controls to persist data between page post backs. You can set View State on/off for each control using EnableViewState property. By default, EnableViewState property will be set to true. View state mechanism poses performance overhead. View state information of all the controls on the page will be submitted to server on each post back. To reduce performance penalty, disable View State for all the controls for which you don't need state. (Data grid usually doesn't need to maintain state). You can also disable View State for the entire page by adding EnableViewState=false to @page directive. View state data is encoded as binary Base64 - encoded which add approximately 30% overhead. Care must be taken to ensure view state for a page is smaller in size. View State can be used using following syntax in an ASP.NET web page.

// Add item to ViewState

ViewState["myviewstate"]  = myValue;

 

//Reading items from ViewState
Response.Write(ViewState["myviewstate"]);



Example:

Output

Advantages:

• Simple for page level data
• Encrypted 
• Can be set at the control level

Disadvantages:

• Overhead in encoding View State values
• Makes a page heavy