Using reflect, how do you set the value of a struct field?

having a rough time working with struct fields using reflect package. in particular, have not figured out how to set the field value.

type t struct { fi int; fs string }
var r t = t{ 123, "jblow" }
var i64 int64 = 456

1. getting Name of field i - this seems to work

   var field = reflect.TypeOf(r).Field(i).Name

2. getting value of field i as a) interface{}, b) int - this seems to work

   var iface interface{} = reflect.ValueOf(r).Field(i).Interface()

   var i int = int(reflect.ValueOf(r).Field(i).Int())

3. setting value of field i - try one - panic

   reflect.ValueOf(r).Field(i).SetInt( i64 )

   panic: reflect.Value·SetInt using value obtained using unexported field

   assuming it did not like field names "id" and "name", so renamed to "Id" and "Name"

   a) is this assumption correct?

   b) if correct, thought not necessary since in same file / package

4. setting value of field i - try two (with field names capitalized ) - panic

   reflect.ValueOf(r).Field(i).SetInt( 465 )

   reflect.ValueOf(r).Field(i).SetInt( i64 )

   panic: reflect.Value·SetInt using unaddressable value

Instructions below by @peterSO are thorough and high quality

Four. this works:

reflect.ValueOf(&r).Elem().Field(i).SetInt( i64 )

he documents as well that the field names must be exportable (begin with capital letter)