Multidimensional arrays were used to represent tables of information and game boards. Nested loops are needed to manipulate the elements of a mutidimensional array in a systematic way. The correspondence between the loop-control variables and the array subscripts determines the order in which the array elements are processed.
Also in this chapter, we introduced variant records. A variant record is one that can have one of several structures, depending on the value of a special field called the discriminant. We used variant records to represent employee records and geometric figures.
The new Ada constructs introduced in this chapter are described in Table 12.1.
Table 12.1
Construct Effect
Declaring Multidimensional Arrays
SUBTYPE Weeks IS Positive RANGE 1..52; YearMatrix describes a two- TYPE Days IS dimensional array with ( Mon,Tue,Wed,Thu,Fri,Sat,Sun); 52 rows and 7 columns (days of the week). TYPE YearMatrix IS ARRAY( Weeks,Days) OF Float; Sales is an array of this type and can Sales : YearMatrix; store 364 float numbers.
Multidimensional Array References
Sales := ( OTHERS=>( OTHERS=>0.0)); Initializes all elements
of Sales to zero.
Ada.Float_Text_IO.Put(Item=>Sales(3, Mon)); Displays the element of
Sales for Monday of week 3.
Ada.Float_Text_IO.Get(Item=>Sales(1, Sun)); Reads the value for the
first Sunday into Sales.
TotalSales := 0.0; Finds the total sales for
FOR Week IN Weeks LOOP the entire year.
FOR Today IN Days LOOP
TotalSales := TotalSales + Sales( Week,Today);
END LOOP;
END LOOP;
Variant Record Declaration
A record type with a
TYPE KidKind IS ( Girl, Boy); variant part is declared.
The discriminant is an
TYPE Child( Sex: KidKind:=Girl) IS RECORD enumeration value.
First: Character; Each record variable
Last: Character; can store two
Age: Natural; characters and an integer.
One variant part can
CASE Sex IS store two float values,
WHEN Girl => and the other can store
Sugar: Float; three integer values.
Spice: Float;
WHEN Boy =>
Snakes: Integer;
Snails: Integer;
Tails: Integer;
END CASE;
END RECORD;
Kid : Child; Kid is a Child record.
Referencing a Record Variant
Uses a CASE statement to
CASE Kid.Sex IS read data into the variant
WHEN Girl => part of the record Kid.
Ada.Text_IO.Put(Item => "Lbs. of sugar>");
Ada.Float_Text_IO.Get
(Item=>Kid.Sugar); If discriminant is Girl,
WHEN Boy => reads a value into the
Ada.Integer_Text_IO.Put
(Item=>"No. of snakes>"); field Kid.Sugar; if the
Ada.Integer_Text_IO.Get(Item=>Kid.Snakes); discriminant is Boy, reads
END CASE; a value into the field
Kid.Snakes.
Float) in each column of a two-dimensional array,
Table, with data type ARRAY (1..5, 1..3) OF Float.
How many column sums will be displayed? How many elements are included in each
sum?
Catcher, Pitcher,
FirstBase, and so on) for each of 15 baseball teams in each of two
leagues (American and National).
Table has N subscripts, the array
elements are placed in memory in the order Table(1,1,...,1,1),
Table(1,1,...,1,2), Table(1,1,...,1,3), and so on.
Then the next-to-last subscript is changed and the elements
Table(1,1,...,2,1), Table(1,1,...,2,2),
Table(1,1,...,2,3) ... are placed. The first subscript will be the
last one that changes.
FOR loops
ColumnSum := 0.0;
FOR Column IN 1..3 LOOP
ColumnSum := 0.0;
FOR Row IN 1..5 LOOP
ColumnSum := ColumnSum + Table(Row,Col);
END LOOP;
Ada.Text_IO.Put(Item=>"Sum for column ");
Ada.Integer_Text_IO.Put(Item=>Column, Width=>1);
Ada.Text_IO.Put(Item=>"is ");
Ada.Integer_Text_IO.Put(Item=>ColumnSum);
END LOOP;
Three column sums, five elements added per column.
TYPE Position IS (Pitcher, Catcher, FirstBase, SecondBase,ThirdBase,
ShortStop, LeftField, CenterField, RightField);
TYPE League IS (American, National);
SUBTYPE Teams IS Positive RANGE 1..15;
TYPE BAArray IS ARRAY (League, Teams, Position) OF Float;
(1..4), (2..3), and
(5..7), draw storage layouts for both row-major and column-major
order.
Supplies, which consists
of either Paper, Ribbon, or Labels. For
Paper, the information needed is the number of sheets per box and
the size of the paper. For Ribbon, the size, color, and kind
(Carbon or Cloth) are needed. For
Labels, the size and number per box are needed. For each supply,
the cost, number on hand, and reorder point must also be stored. Use whatever
data types are appropriate for each field.
Vehicle. If the vehicle is a
Truck, then BedSize and CabSize are
needed. If the vehicle is a Wagon, the third seat or not is needed
(Boolean). If the vehicle is a Sedan, the information
needed is TwoDoor or FourDoor. For all vehicles, we
need to know whether the transmission is Manual or
Automatic; if it has AirConditioning,
PowerSteering, or PowerBrakes (all
Boolean); and the gas mileage. Use whatever data types are
appropriate for each field.
Candidate Candidate Candidate Candidate
Precinct A B C D
1 192 48 206 37
2 147 90 312 21
3 186 12 121 38
4 114 21 408 39
5 267 13 382 29
Write a program to do the following:
a. Display the table with appropriate headings for the rows and columns.
b. Compute and display the total number of votes received by each candidate and the percent of the total votes cast.
c. If any one candidate received over 50% of the votes, the program should print a message declaring that candidate the winner.
d. If no candidate received 50% of the votes, the program should print a message declaring a run-off between the two candidates receiving the highest number of votes; the two candidates should be identified by their letter names.
e. Run the program once with the above data and once with candidate C receiving only 108 votes in precinct 4.
Spiders (
Program
10.19) as suggested in Section 12.3, to detect spider collisions in the
room. Modify the program Draw_Many_Boxes (
Program
10.20) so that something useful is done when a collision is detcted.
Copyright © 1996 by Addison-Wesley Publishing Company, Inc.