enum_type_qualification.adb.npp

来自「This contains the following topics and m」· NPP 代码 · 共 27 行

with text_io; use text_io;
procedure Enum_type_qualification is
--In some situations an expression's or value's type can be ambiguous.
   --For example,
   type primary is (Red,Green,Blue,yellow,orange);
   subtype new_primary is primary range Red ..Blue;
   type secondary is (Red,Green,sai,gray,Blue);
  -- type rainbow is new integer;
   --subtype new_color is rainbow range 1..20;
   var_primary,age :primary;
   var1_primary :secondary;
   i :integer;
begin
   --var1_primary := var_primary; -- error
   age := var_primary;-- no error
   --for i in red..blue loop -- this is ambiguous
-- Here we need to specify precisely what type is required. This is done with type qualification.
	for i in primary'(red)..primary'(blue) loop
	-- for i in rainbow'(red)..blue loop -- only one qualification needed
	--for i in primary'(red)..blue loop
--Type qualification does not change a value's type. It merely informs the compiler of what type the programmer thinks it should be.
       put_line("hai");
        end loop;
        --end loop;
       -- end loop;
        end Enum_type_qualification;