1. RECORDS Introduction Declaring a record Using records
The with...do statements
Array of records

2. 0. Introduction
to store and process related data items of different types
E.g., an employee record contains:
employee’s name (string),
sex (character),
age (integer),
monthly salary (real)

3. 1. Declaring a record record a record is
a collection of related records.
structured data type record
record
<field identifier-1> : <data type-1>;
<field identifier-2> : <data type-2>; .
<field identifier-i> : <data type-i>;
end.

4. 1. Declaring a record programmer’s name Example
Suppose we want to keep a record for a programmer of a software house, which contains a field for each of the following:
programmer’s name
(John Wong)
sex (M)
age (22)
monthly salary ( )

5. 1. Declaring a record preferable with arrays var Programmer : record
Name : string;
Sex : char;
Age : integer;
MonthlySalary : real
end;
type EmployeeInfo = record
var Programmer : EmployeeInfo;
preferable
with
arrays

6. 2. Using Records Accesssing record fields Assigning values to a record
Copying records

7. 2.1 Accessing record fields
John Wong M
Programmer
Name Sex Age MonthlySalary
<record name>.<field name>
e.g., accessing record Programmer
Programmer.Name
Programmer.Sex
Programmer.Age
Programmer.MonthlySalary
using writeln statements to output

8. 2.2 Assigning values to a record
by assignment statements
Programmer.Name := ‘Mary Chan’;
Programmer.Sex := ‘F’;
Programmer.Age := 20;
Programmer.MonthlySalary := 12000;
by input statements
readln( Programmer.Name );
readln( Programmer.Sex );
readln( Programmer.Age);
readln( Programmer.MonthlySalary );

9. 2.3 Copying records
to transfer information in one record to another record
Example
type EmployeeInfoA = record ... end;
EmployeeInfoB = record ... end;
var Employee1, Employee2 : EmployInfoA;
Employee3 : EmployInfoB; ..
Employee1 := Employee2;
Which one is correct?
Employee1 := Employee3;

10. 3. The with...do statements with <record name> do
for input statements for the record Programmer in 2.2
readln( Programmer.Name );
readln( Programmer.Sex );
readln( Programmer.Age);
readln( Programmer.MonthlySalary );

11. 3. The with...do statements with <record name> do
can be written as:
with Programmer do
begin
readln(Name);
readln(Sex);
readln(Age);
readln(MonthlySalary);
end;

12. 4. Array of Records
Problem: a telephone directory which contains the names and the phone numbers of a number of friends.
What kind of array is the following words represent?
Size = 100;
type NameArray = array[1..Size] of string[20];
PhoneNoArray = array[1..Size] of string[8];
var Name : NameArray;
PhoneNo : PhoneNoArray;
PARALLEL ARRAY

13. 4. Array of Records record + array = an array of records
const Size = 100;
type Str20 = string[20];
Str8 = string[8];
Info = record
Name : Str20;
PhoneNo : Str8;
end;
InfoArray = array[1..Size] of Info;
var Friend : InfoArray;

14. 4. Array of Records
Name[1] PhoneNo[1]
Name[2] PhoneNo[2]
Name[3] PhoneNo[3]
. .
Name[100] PhoneNo[100]
Fig.1 Parallel arrays
Name PhoneNo
Friend[1]
Friend[2]
Friend[3] .
Friend[100]
Fig.2 An array of records