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Useful Ada Information

This article provides helpful information and assistance for programming assignments in Ada, including clarifications, handling exceptions, and using user-defined types.

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Useful Ada Information

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  1. Useful Ada Information Help for programming assignment

  2. Clarifications • You must read and write the moves directly – you may NOT convert them to strings for printing. • You should print out the number of ties as well as the number of computer wins and user wins • You need to handle the situation where the user types in rack or scisssors or piper (for example) • If an exception occurs, you need to handle it and continue until either the user or the computer has won 3 games. • Don’t use use clauses

  3. Declaring a user-defined type (enumeration type) • typetypename is(elementList ); • elementList → element • elementList → element , {elementList} • element can not be numeric • element can not contain a reserved word • element can not have spaces in it

  4. Examples • type car is (ford, chevy, lincoln, bmw); • type city is (rome, naples, bologna); • type die is (1,2,3,4,5,6); • type die is (one, two, three, four, five,six); • type city is (new york, paris); • type city is (old town, paris);

  5. Instantiating an enumeration type • package name_io is new ada.text_io.enumeration_io (enum => type); • instantiation allows reading and writing of enumerated type variables • enum is the formal parameter name • => is called arrow • this example uses named parameter passing • formal parameter name is NOT required

  6. Here’s the Ada specification for the procedure to print an integer Procedure put (item : in Num; width : in Field := Default_Width; base : in Number_Base := Default_base; • The default_base is 10 • The default_width is num’width • Given an integer variable named number • The following are equivalent calls to this procedure Ada.integer_text_io.put (number); Ada.integer_text_io.put (item => number);

  7. Procedure put (continued) • Given an integer variable named number, suppose you want the column width of your output to be 10 and you want to use the default base • The following statements produce the same results • Ada.integer_text_io.put (number, 10); • Ada.integer_text_io.put (item => number, width => 10); • Ada.integer_text_io.put (width => 10, item => number); • Ada.integer_text_io.put (item => number, width => 10, base => 10; • Ada.integer_text_io.put (number, 10, 10); • Ada.integer_text_io.put (base =>10, item => number, width => 10);

  8. Examples • type car is (ford, chevy, lincoln, bmw); • package car_io is new ada.text_io.enumeration_io (enum => car); • type city is (rome, naples, bologna); • package city_io is new ada.text_io.enumeration_io (city);

  9. Examples • type car is (ford, chevy, lincoln, bmw); • package car_io is new ada.text_io.enumeration_io (enum => car); • myCar : car; • car_io.get( myCar); • car_io.put (myCar);

  10. Enumeration types have attributes • typename’pos • typename’val • typename’first • typename’last • The enumeration type’s element list is ordered • The first element is in position 0

  11. Ada Random Number Generator • The information on random number generation can be found in the Language Reference Manual at • http://www.adahome.com/rm95/rm9x-A-05-02.html • Here is an example of code from the above site using Ada’s random number generator • with Ada.Numerics.Discrete_Random; • procedure Dice_Game is • subtype Die is Integer range 1 .. 6; • subtype Dice is Integer range 2*Die'First .. 2*Die'Last; • package Random_Die is new Ada.Numerics.Discrete_Random (Die); • use Random_Die; • G : Generator; • D : Dice; • begin • Reset (G); -- Start the generator in a unique state in each run • loop -- Roll a pair of dice; sum and process the results • D := Random(G) + Random(G); ... • end loop; • end Dice_Game;

  12. Ada subprograms • can be separately compiled • can be separately executed • execution only shows if there is output • ada subprogram specifications • have extension .ads • header ends in a semicolon • Ada subprogram bodies • have extension .adb • header ends in reserved word is

  13. Ada functions • Function body (i.e. Dot_Product.adb) below comes from the language reference manual http://www.adahome.com/rm95/rm9x-06-03.html function Dot_Product(Left, Right : Vector) return Real is Sum : Real := 0.0; begin Check(Left'First = Right'First and Left'Last = Right'Last); for J in Left'Range loop Sum := Sum + Left(J)*Right(J); end loop; return Sum; end Dot_Product;

  14. Ada procedures • subprogram_body ::= subprogram_specification is declarative_part begin handled_sequence_of_statements end [designator]; procedure Push(E : in Element_Type; S : in out Stack) is begin if S.Index = S.Size then raise Stack_Overflow; else S.Index := S.Index + 1; S.Space(S.Index) := E; end if; end Push; above Procedure example can be found at http://www.adahome.com/rm95/rm9x-06-03.html

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