c# - How declare Textbox value (using Controls.Find) in public partial class without error? -

hi have code create new variable textbox not exist yet, can created on runtime. work great, see code bellow

public void btnapagar_click(object sender, eventargs e) {     textbox txtacessorio4 = (textbox)gpbcategoria.controls.find("txtacessorio4", false).firstordefault();      if (txtacessorio4 != null && txtacessorio4.text == "" && lblacessorio4.name == "lblacessorio4")     {         messagebox.show("perfect");     } } 

problem use created variable on places in code too, i tried:

public partial class cad_produto_acessorios_novo : form {     textbox txtacessorio4 = (textbox)gpbcategoria.controls.find("txtacessorio4", false).firstordefault(); }  public void btnapagar_click(object sender, eventargs e) {         if (txtacessorio4 != null && txtacessorio4.text == "" && lblacessorio4.name == "lblacessorio4")     {          messagebox.show("perfect");     } } 

but had bellow error on public partial class(gpbcategoria groupbox name):

error   1   field initializer cannot reference non-static field, method, or property 'infoearth_cad_cliente.cad_produto_acessorios_novo.gpbcategoria 

somebody know how solve it?

many of recent questions go same direction.

if want access control (like label or textbox) have created @ runtime need kind of container (an array or list). way .net framework checks during runtime if control present in container.

void btnapagar_clickclick(object sender, eventargs e) {     // test if textbox 4 exist counting number of added textboxes     if(textboxlist.count ==4 || textboxlist.count > 4)     {         // list , array 0 based --> index 3 4th textbox         messagebox.show("perfect have "                          + " @ least 4 boxes , name is: "                          + textboxlist[3].name);          }else {         messagebox.show("number of textboxes not enough - add more");     } } 

instead of using (textbox)gpbcategoria.controls.find("txtacessorio4", false).firstordefault(); can access list index "future" instance textbox_4

you may take @ my example project , play around it. can openend sharpdevelop 4.3.