Aims

• Know what is meant by the term array, including the difference between 1D and 2D arrays.

• Know what is meant by the term record structure.

• Be able to write pseudocode that uses arrays and records.

Arrays are list of variables with the same data type and have same identifier name, can be 1D (stores in linear, single row and data is in consecutive locations), or 2D (stores in grid-like structure)

One-dimensional Array

Syntax:

E.g. 1D array - letters with 30 spaces

DECLARE letters : ARRAY [1:30] OF STRING

Each element is given an index number which represents its position e.g. letters [1] is X

Two-dimensional Arrays

Syntax (same as 1D but need to specify second dimension)

E.g. 2D array - noughtsAndCrosses, 3 rows and 3 columns

DECLARE noughtsAndCrosses : ARRAY [1:3, 1:3] OF CHAR

Each element is given an index number to represent its position e.g. noughtsAndCrosses [3:2] is O

Defining Records

Record structures allows storage of multiple related items of different data types together

Syntax:

E.g. Record structure called users to store details of User ID, first name, surname and DOB

TYPE users

DECLARE userID : INTEGER

DECLARE firstName : STRING

DECLARE surname : STRING

DECLARE dateOfBirth : DATE

ENDTYPE

Once the record structure has been created, data can then be added:

DECLARE user1 : users

user1.userID ← 1

user1.firstName ← “Leroy”

user1.surname ← “Johnson”

user1.dateOfBirth ← 02/01/95

Linear search e.g. (not taught, e.g. from question)

DECLARE nameToSearch : STRING

DECLARE count : INTEGER

INPUT nameToSearch

FOR count ← 1 TO 4

// IF names[count] = nameToSearch THEN

// OUTPUT “The name exists”

// ENDIF

Next count

Change data in a 2D array e.g (not taught e.g. from question)

scores [2:3] ← 6