10.1 Records

Records allow the user (programmer) to create their own data type. A record (CIE's terminology) is a user-defined composite data type. That is, it is a data type, defined by the user that comprises of primitive data types. Put another way, it references existing data types.

Pseudocode syntax for records (above) can be found in the pseudocode guide, as well as examples below.

TYPE Team

DECLARE TeamName : STRING

DECLARE AwayWins : INTEGER

DECLARE HomeWins : INTEGER

DECLARE Draws : INTEGER

DECLARE NextMatch : Date

ENDTYPE

DECLARE MHUnited : Team

MHUnited.TeamName ß “Mill Hill United”

MHUnited.Draws ß 5

Programmatically, only VB.NET supports records in the same way and use as pseudocode. However, a record can be viewed as a cutdown version of a class (A2 content), and as such, all three programming languages support classes and therefore can use a version of a record.

The examples below are taken from the Langfield and Duddel textbook (chapt. 26). They give examples of how to create a record in each language and examples of creating a structure variable or an array/list of records. When you come to do your own, it is common to have arrays/lists of structures.

VB.NET

VB note: Arrays work as in pseudocode. However, if you create a list of a structure type, you need to declare accordingly (example below).

Note, when using lists (instead of arrays), you need to create a single variable of your structure, populate and add this to the list. An example is given below.

Module Module1

Structure Person

Dim FirstName As String

Dim LastName As String

Dim DoB As Date

End Structure

Sub Main()

Dim Teacher As List(Of Person)

Dim tempTeacher As Person ' this variable, of type person is what is added to the list

tempTeacher.FirstName = "Fred")

tempTeacher.LastName = "Smith"

tempTeacher.DoB = #2/5/1981# ' uses US style date format for literal dates

Teacher.Add(tempTeacher)

End Sub

End Module

Python

Python does not support records in the way that pseudocode or VB does. Instead, you must use a class. Classes are discussed in the A2 year and are a different way (paradigm) of programming. However, the text book example demonstrates how they can be carried out.

Java

Java does not support records in the way that pseudocode or VB does. Instead, you must use a class. Classes are discussed in the A2 year and are a different way (paradigm) of programming. However, the text book example demonstrates how they can be carried out.

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