Enumerated Types





Introduction to Enumerated Types





Concept



Enumerated Types Create New Literals!



Enumerated Types - Questions





Operations Available with Enumerated Types





Some Basic Operations

  • Example (prettified)
  •  
        -- Illustrates:
        --    declaring variables, assignment, relational operators, in, ranges
        with Ada.Text_io; use Ada.Text_io;
    
        procedure enum1 is
    
            type Day is (Sunday, Monday, Tuesday, Wednesday, 
                            Thursday, Friday, Saturday);
    
            today: Day;
    
        begin
            today := Thursday;
    
            if today = Friday then
                put("We made it!");
            end if;
    
            for d in Sunday .. Saturday loop
    
                if d in Monday .. Friday then
                    put("It's a work day.");
    
                    if <  Wednesday then 
                        put("Just started the week!.");
                    end if;
    
                else
                    put("It's the weekend!");
                end if;
    
            end loop;
    
        end enum1;
      


    I/O of Enumerated Types



    Advantages of Enumeration_IO



    Package Enumeration_IO



    More Operations: Attributes of Enumerated Types





    Type Checking with Enumerated Types





    Enumerated Types are Strongly Typed

     
            with Ada.Text_io; use Ada.Text_io;
    
            procedure enum1a is
    
            type Color is (Red, Blue, Green);
    
            type Day is (Sunday, Monday, Tuesday, Wednesday, 
                            Thursday, Friday, Saturday);
    
            c: Color;
            d: Day;
            n: Natural := 1;
    
            begin
            c := Red;
    
            d := Friday;
    
            c := Friday;          -- Compile error
                                    
            c := d;               -- Compile error
                                    
            c := 1;               -- Compile error
                                    
            d := 1;               -- Compile error
                                    
            n := c;               -- Compile error
                                    
            c := n;               -- Compile error
    
            if d = Blue then      -- Compile error
                put("It's Friday!");
            end if;
    
            end enum1a;
      


    Ambiguous Values



    Enumerated Type Values and Variables, etc





    Array Indices and Subranges





    Enumerated Types as Array Indices



    Subtypes (ie Subranges) of Enumeration





    Predefined Enumeration Types





    Types Boolean and Character





    Enumerated Types in Other Languages





    Java 1.4 and Earlier (and Sometimes Later)



    C and C++



    Java 1.5 and Later






    Motivation for Enumerated Types





    Motivation





    A Final Example using Enumerated Types





    An Example Using Enumeration Types