c# - Textbox doesn't clear -

i fill texboxes with:

foreach (user u in userinfo) {     txtnickname.text = u.nickname;     txtfirstname.text = u.firstname;     txtlastname.text = u.lastname;     txtemail.text = u.email; } 

my textboxes filled data database.

for example fill new values in of texboxes , click on button, happens this:

if (txtnickname.text != string.empty && txtfirstname.text != string.empty && txtlastname.text != string.empty && txtemail.text != string.empty) {    //todo } 

but when debug: values of textboxes old values (the values foreach-loop), , not new values fill in textboxes.

why happening? i'm loading data database in textboxes, after i'm changing values of textboxes myself, , when debug textbox values still database-values (see foreach-loop).

if first loop executed in page_load event should sure don't execute again when page posted result of clicking on button.

more info in page.ispostback on msdn

private void page_load() {     if (!ispostback)     {         // code should executed when page being          // rendered first time not when responding postback          // raised <runat="server">  controls         userinfocollection userinfo = getuserinfocollection();          foreach (user u in userinfo)         {             txtnickname.text = u.nickname;             txtfirstname.text = u.firstname;             txtlastname.text = u.lastname;             txtemail.text = u.email;         }     } }