Tuesday 4/2 Week 11

Tuesday 4/2 Week 11

Chapter 9

Objectives

Records

1. What is a record?

· A record is a

· Example: an entry in an address book

· One entry might contain:

Last Name

First Name

Street address

City

State

Zip Code

Area Code

Phone number

Birth date

· NameSize : CONSTANT := 20;

SUBTYPE NameType IS String(1..NameSize);

SUBTYPE StreetType IS String(1..2*NameSize);

SUBTYPE StateType IS String(1..2);

SUBTYPE ZipType IS Positive RANGE 00000..99999;

SUBTYPE AreaCodeType IS Positive RANGE 111..999;

SUBTYPE PhoneType IS Positive RANGE 1111111..9999999;

TYPE AddressEntry IS RECORD

LastName : NameType;

FirstName : NameType;

SteetAddress : StreetType;

City : NameType;

State : StateType;

ZipCode: ZipType;

AreaCode : AreaCodeType;

Phone : PhoneType;

BirdthDate : Date;

END RECORD;

· This record is now a new type and we can declare variables of type AddressEntry

Julie : AddressEntry;

Dad : AddressEntry;

2. Getting at the information in a RECORD

· a which is the varname.field

· Julie.LastName := “Strain “;

Julie.FirstName := “Julie “;

Julie.StreetAddress := “15121 Sobey Rd. “;

Julie.City := “Yreka “;

Julie.State := “CA”;

Julie.ZipCode := “95090”;

Julie.AreaCode := “949”;

Julie.Phone := “2345678”;

Julie.Birthday := Dates.MakeDate(12, 31, 1980);

· Once each field has a value, the field selector is used like any other variable

Ada.Text_IO.Put(Item => Julie.City);

· E.g. page 371

3. Reading in records

· E.g. page274

4. Aggregate Assignment

· It is also possible to use an aggregate assignment, so that we may assignment all of the parts of a record with one statement.

Julie := (LastName => “Strain “,

FirstName => “Julie “,

StreetAddress => “15121 Sobey Rd. “,

City => “Yreka “,

State => “CA”,

ZipCode => “95090”,

AreaCode => “949”,

Phone => “2345678”,

Birthday => Dates.MakeDate(12, 31, 1980));

· In an aggregate assignment, you must

· It is also possible to assign the parameters with out the formal names, but

· In general we use the formal parameters because it is much more clear and avoids accidentally incorrectly assigning a field.

5. Hierarchical records

· We can have records whose fields are records. See BirthDate for an example

· Page 381, type Employee

· When a field is also a record it is accessed like varname.fieldrec1.field

· Page 383, reading in a hierarchical record