The followingCodeDisplays the number of "Page return" times.
Note that the value of session ["postbackcount"] may be null.
Use ?? When the operator is complete, when it is null, 0 is returned.
Using system; <br/> using system. collections; <br/> using system. configuration; <br/> using system. data; <br/> using system. LINQ; <br/> using system. web; <br/> using system. web. security; <br/> using system. web. ui; <br/> using system. web. UI. htmlcontrols; <br/> using system. web. UI. webcontrols; <br/> using system. web. UI. webcontrols. webparts; <br/> using system. XML. LINQ; <br/> using system. threading; <br/> namespac E Ajax <br/>{< br/> Public partial class _ default: system. web. UI. page <br/> {<br/> protected int postbackcount <br/> {<br/> Get <br/> {<br/> return (INT) (session ["postbackcount"]? 0); <br/>}< br/> set <br/>{< br/> session ["postbackcount"] = value; <br/>}</P> <p> protected void page_load (Object sender, eventargs E) <br/>{< br/> literal1.text = (++ postbackcount ). tostring (); <br/>}< br/>