asp.net - difference between Page_Init vs OnInit -

i had interview week ago , 1 of questions difference between oninit, page_init , prerender. 1 preferable?

page_init event handler page.init event, typically see if add handler within class itself.

oninit method raises init event.

the 2 can seen being equivalent if used within subclass, there difference: init exposed other types, oninit method protected , responsible raising event, if override oninit , fail call base.oninit init event won't fired. here's how looks like:

public class page {      public event eventhandler init;     public event eventhandler load;      protected virtual void oninit(object sender, eventargs e) {         if( this.init != null ) this.init(sender, e);     }      protected virtual void onload(object sender, eventargs e) {         if( this.load != null ) this.load(sender, e);     }      public void executepagelifecylce() {         this.oninit();         // houskeeping here         this.onload();         // further housekeeping         this.dispose();     } }  public class mypage : page {      public mypage() {          this.init += new eventhandler( mypage_init );     }      private void mypage_init(object sender, eventargs e) {         // no additional calls necessary here     }      protected override void onload(object sender, eventargs e) {         // must make following call .load event handlers called         base.onload(sender, e);     } } 

generally overriding onload / oninit methods faster (but microptimisation, you're saving couple of instructions delegate dispatch) , many "purists" argue using events unnecessarily ugly :)

another advantage of not using events avoiding bugs caused autoeventwireup can cause events called twice each page load, not desirable if event-handlers not idempotent.