Pseudocode Foundations & Conventions: Data Types Used In AS Level Pseudocode (Copy)

Data Types Used In AS Level Pseudocode

Purpose Of Data Types In Pseudocode

• Data types define:
  • What kind of data a variable can store
  • How that data is processed
• Examiner checks:
  • Correct data type choice
  • Correct usage in operations
• Wrong data type selection leads to:
  • Logic errors
  • Loss of method marks

Core AS Level Data Types (Must Know)

INTEGER Data Type

INTEGER Declaration And Use

DECLARE Age : INTEGER
DECLARE Count : INTEGER

Age ← 18
Count ← Count + 1

• INTEGER cannot store decimal values
• Used heavily in loops and array indexing

REAL Data Type

REAL Declaration And Use

DECLARE Average : REAL
Average ← Total / Count

• Use REAL whenever division may produce decimals
• Using INTEGER for averages causes truncation

Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change AS Level Computer Science Full Scale Course

STRING Data Type

STRING Declaration And Use

DECLARE Name : STRING
Name ← "Ali"

STRING In Output

OUTPUT "Student Name = ", Name

• STRING values must be enclosed in quotation marks
• Used for names, messages, labels

CHAR Data Type

CHAR Declaration And Use

DECLARE Grade : CHAR
Grade ← 'A'

• Do not store full words in CHAR
• Commonly used for grades and codes

BOOLEAN Data Type

BOOLEAN Declaration And Use

DECLARE Found : BOOLEAN
Found ← FALSE

BOOLEAN In Conditions

IF Found = TRUE THEN
    OUTPUT "Value found"
ENDIF

• BOOLEAN variables are called flags
• Must always be initialised

Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change AS Level Computer Science Full Scale Course

ARRAY Data Type (Structured Data)

ARRAY Declaration

DECLARE Marks : ARRAY[1:10] OF INTEGER

ARRAY Usage

FOR i ← 1 TO 10
    OUTPUT Marks[i]
ENDFOR

• Index must match declared bounds
• ARRAY elements inherit the declared data type

RECORD Data Type (Composite Data)

RECORD Declaration

RECORD StudentType
    Name : STRING
    Age : INTEGER
    Grade : CHAR
ENDRECORD

RECORD Variable And Use

DECLARE Student : StudentType
Student.Name ← "Ali"
Student.Age ← 18
Student.Grade ← 'A'

• RECORD fields can be different data types
• Improves data organisation

Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change AS Level Computer Science Full Scale Course

FILE Data Type (AS Level Scope)

FILE Usage Example

OPENFILE DataFile FOR READ

WHILE NOT EOF(DataFile) DO
    READFILE DataFile, Line
    OUTPUT Line
ENDWHILE

CLOSEFILE DataFile

• FILE is treated as a data structure
• Data read from file usually stored in STRING variables

Choosing The Correct Data Type (Examiner Focus)

Common Data Type Mistakes And Fixes

Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change AS Level Computer Science Full Scale Course

Data Types In Expressions

Average ← Total / Count

• Result of division stored in REAL
• Examiner expects correct type promotion

Data Types With Conditions

IF Grade = 'A' THEN
    OUTPUT "Excellent"
ENDIF

Examiner-Safe Data Type Checklist