Pseudocode Overview

This page can serve as a quick lookup for the CIE pseudocode examples as given in the specification. ALWAYS refer to the CAIE Pseudocode Teacher Guide as that will always hold up-to-date content for your exam.

Data Types (10.1)

Pseudocode will use the following data types:

• INTEGER

• REAL

• CHAR

• STRING

• BOOLEAN

• DATE

• ARRAY

• FILE

Arrays (10.2)

Given pseudocode will use the following structures:

DECLARE <identifier> : ARRAY[<lbound>:<ubound>] OF <datatype>

DECLARE <identifier> : ARRAY[<lbound1>:<ubound1>,[<lbound2>:<ubound2>] OF <datatype>

Files (10.3)

Use pseudocode for file handling:

OPENFILE <filename> FOR READ/WRITE/APPEND // Open file (understand the difference between various file modes)

READFILE <filename>,<string variable> // Read a line of text from the file

WRITEFILE <filename>,<string variable> // Write a line of text to the file

CLOSEFILE <filename> // Close file

EOF(<filename>) // function to test for the end of the file - returns TRUE or FALSE

Programming Basics (9-11)

Given pseudocode will use the following structures:

DECLARE <identifier> : <data type> // declaration

CONSTANT <identifier> = <value>

<identifier> ← <value> or <expression> // assignment

INPUT <identifier>

OUTPUT <string> // this is a literal string, encased in quotation marks ""

OUTPUT <identifier(s)>

Concatenation uses '&' symbol now, rather than comma, as in previous specification.

Selection (11.2)

Use an ‘IF’ structure including the ‘ELSE’ clause and nested IF statements. Given pseudocode will use the following structure:

IF <condition>

THEN

<statement(s)>

ENDIF

–– or, including an ‘else’ clause:

IF <condition>

THEN

<statement(s)>

ELSE

<statement(s)>

ENDIF

Use a ‘CASE’ structure. Given pseudocode will use the following structure:

CASE OF <identifier>

<value 1>: <statement>

<value 2>: <Statement>

...

ENDCASE

–– alternatively, using optional OTHERWISE:

CASE OF <identifier>

<value 1>: <statement>

<value 2>: <Statement>

...

OTHERWISE <statement>

ENDCASE

Iteration (11.2)

Use a ‘count-controlled’ loop. Given pseudocode will use the following structure:

FOR <identifier> ← <value1> TO <value2>

<statement(s)>

NEXT <identifier>

–– alternatively:

FOR <identifier> ← <value1> TO <value2> STEP <value3>

<statement(s)>

NEXT <identifier>

Use a ‘post-condition’ loop. Given pseudocode will use the following structure:

REPEAT

<statement(s)>

UNTIL <condition>

Use a ‘pre-condition’ loop. Given pseudocode will use the following structure:

WHILE <condition>

<statement(s)>

ENDWHILE

Procedures/Functions (Structured Programming) (11.3)

Given pseudocode will use the following structure for procedure definitions:

PROCEDURE <identifier>

<statement(s)>

ENDPROCEDURE

Show understanding of passing parameters by reference:

PROCEDURE <identifier> (BYREF <identifier>: <datatype>)

<statement(s)>

ENDPROCEDURE

show understanding of passing parameters by value:

PROCEDURE <identifier> (BYVALUE <identifier>: <datatype>)

<statement(s)>

ENDPROCEDURE

A call is made to the procedure using CALL <identifier> ()

Given pseudocode will use the following structure for function definitions:

FUNCTION <identifier> RETURNS <data type> // function has no parameters

<statement(s)>

ENDFUNCTION

FUNCTION <identifier> (<identifier>: <data type>) RETURNS <data type> // function has one or more parameters

<statement(s)>

ENDFUNCTION

–– a function is used in an expression, for example:

• x ← SQRT(n)

• WHILE NOT EOF(<filename>)