Programmatically make the SharePoint choice field default value to null

I have a custom list "cl1" which has a choice field "Choice". The values for the choice field are "A", "B","C" & "D".
If you create a Choice column through UI the default value will be selected as "A".

In this we will be seeing how to change the choice field default value to null using SharePoint object model.


using (SPSite site = newSPSite("http://serverName:1111/sites/sample"))
{ using (SPWeb web = site.RootWeb)
{ SPList list = web.Lists.TryGetList("cl1"); foreach (SPField field in list.Fields)
{ if (field.Title == "Choice")
{
field.DefaultValue = null;
field.Update();
}
}
list.Update();
}
}