AS Level10Paper 2 — Problem-solving and Programming

Data Types and Structures

Choosing the right container: simple types, records, arrays and files.

YOU SHOULD BE ABLE TO

Select appropriate data types: integer, real, char, string, Boolean, date.
Define and use records (user-defined types).
Use 1D and 2D arrays, and explain when each is suitable.
Understand serial, sequential and random file organisation.
Read from and write to text and binary files.

RUN THE PSEUDOCODE

Write the pseudocode your syllabus uses and press Run. Assignment is the arrow — type <- and it works the same as ←. Both syllabuses are accepted, so OUTPUT and PRINT both work; where a word differs from the one the exam prints, the runner says so.

PROGRAM

DECLARE Name : STRING
DECLARE Age : INTEGER

Name <- "Bat"
Age <- 14

OUTPUT "Hello ", Name
OUTPUT "Next year you are ", Age + 1

INPUT — ONE VALUE PER LINE

OUTPUT

Press Run to see what it does

TRACE TABLE

Total ← 0
FOR Count ← 1 TO N
    Total ← Total + Count
NEXT Count
OUTPUT Total

STARTN = 5

Count	Total	OUTPUT

One row per pass through the loop. Leave a cell blank if it does not change on that pass.

//Records group related fields

A record lets one variable hold several different types that belong together — far clearer than parallel arrays.

TYPE Student
   DECLARE Name  : STRING
   DECLARE Age   : INTEGER
   DECLARE Grade : CHAR
ENDTYPE

DECLARE Class : ARRAY[1:30] OF Student

Class[1].Name ← "Bat"
Class[1].Age  ← 14

//File organisation

Serial: records in the order they arrived, no order — used for transaction logs. Sequential: records kept in key order — good for processing everything in order. Random (direct): the position is calculated from the key, so any record can be reached immediately — used when fast individual lookups matter.

CHECK YOURSELF

1.Why use a record rather than several parallel arrays?

2.Which file organisation lets you jump straight to a record without reading the others?

3.A transaction log written in the order events happened is which organisation?

Algorithm Design and Problem-solving Programming

RUN THE PSEUDOCODE

PROGRAM

DECLARE Name : STRING
DECLARE Age : INTEGER

Name <- "Bat"
Age <- 14

OUTPUT "Hello ", Name
OUTPUT "Next year you are ", Age + 1

INPUT — ONE VALUE PER LINE

OUTPUT

Press Run to see what it does

Count

Total

OUTPUT

//File organisation

CHECK YOURSELF

1.Why use a record rather than several parallel arrays?

2.Which file organisation lets you jump straight to a record without reading the others?

3.A transaction log written in the order events happened is which organisation?