Records

1
Records
Foundation Studies Course
2
More than 1 datatype

• A record is a user defined data type suitable for
  grouping data elements together.
• All elements of an array must contain the same
  data type. A record overcomes this by allowing
  us to combine different data types together.

3
Where is it applicable?

• Suppose we want to create a data record which
  holds a student name and mark. The student name
  is a packed array of characters, and the mark is
  an integer.
• We could use two separate arrays for this, but a
  record is easier. The method to do this is,
• define or declare what the new data group
  (record) looks like
• create a working variable to be of that type

4
Definition

• TYPE
• RECORD_NAME record
• Var1 data type
• Var 2 data type
• Var 3 data type
• END
• The first portion defines the composition of the
  record identified as RECORD_NAME.
• It consists of a number of parts (called fields).
  
• Each field will have
• Variable Name
• Data Type for the variable name
• And terminates with the reserved word END

5
Declaring Records

• A typical declaration follows
• TYPE
• studentinfo RECORD
• name string
• age integer
• gender char
• registeredboolean
• END
• VAR student1 studentinfo

6
Assigning Values

• Each of the individual fields of a record are
  accessed by using the DOT format,
• recordname.fieldname value or variable
• e.g. student1.name 'JOE BLOGGS '
• student1.age 21
• student1.gender M
• student1.registered TRUE

7
Example - Declarations

• program prog6
• uses CRT
• type
• StudentInfo record
• namestring
• ageinteger
• citystring
• zipinteger
• end
• const
• Max2
• var
• numberinteger
• Students array 1..Max of StudentInfo

8
Example - Input

• Begin
• clrscr
• INPUT
• writeln('Enter Student Details')
• for number1 to Max do
• begin
• write('Name ',number,' ')
• readln(Studentsnumber.name)
• write('Age ',number,' ')
• readln(Studentsnumber.age)
• write('City ',number,' ')
• readln(Studentsnumber.city)
• write('Zip ',number,' ')
• readln(Studentsnumber.zip)
• writeln
• end

9
Example - Output

• clrscr
• OUTPUT
• writeln('These are the Student Details you
  entered')
• for number1 to Max do
• begin
• write(Studentsnumber.name)
• write(' ',Studentsnumber.age)
• write(' ',Studentsnumber.city)
• writeln(' ',Studentsnumber.zip)
• end
• End.

10
Lab 1

• Change Program 6 to be able to be able to store
  30 students with the following details
• Name
• Maths
• English
• Maltese
• Average Mark
• Grade A (80-100) B (60-80) C (50-60) D (40-50)
  F (less than 40)

Name Joe Borg Maths 55 English 68
Maltese 75 Average 66.0 Grade B
11
Lab 2

• The owners of a video shop decided to computerize
  their database and required a program in order to
  enter the data they already had stored on cards.
  Each card had details about a single video,
  namely
• Name of video,
• Reference number,
• Location - Shelf number,
• Type Love(L), Drama(D), Violent(V),
• Available ?
• Write a program to enter 5 items into this
  database and display them in table form.