CAIE 0478 & 9618 Common Operations

5. Common Operations & Built-in Functions

Cambridge pseudocode I/O routines, arithmetic (DIV/MOD), relational operators, Boolean logic, and unified string & numeric built-in functions.

Standard input/output commands, arithmetic operators, relational and Boolean logic, and unified string & numeric built-in functions.

5.1 Input & Output

PSEUDOCODE Run in Sandbox

// runnable
// Input and output demo
DECLARE Answer, Score, Lives : INTEGER
Score <- 10
Lives <- 3
INPUT Answer
OUTPUT "Your answer: ", Answer
OUTPUT Score
OUTPUT "You have ", Lives, " lives left"

5.2 Arithmetic Operators

Operator	Description
`+`	Addition
`-`	Subtraction
`*`	Multiplication
`/`	Division (result is always REAL)
`DIV`	Integer division (quotient only)
`MOD`	Modulus (remainder after division)

5.3 Relational Operators

Operator	Description
`>`	Greater than
`<`	Less than
`>=`	Greater than or equal to
`<=`	Less than or equal to
`=`	Equal to
`<>`	Not equal to

The result of relational operations is always of data type BOOLEAN.

5.4 Logic Operators

The logic operators are AND, OR, and NOT. Operands and results are always BOOLEAN. Use parentheses to make order of operations explicit.

5.5 String Functions & Operations

Function Signature	Description	Example	Syllabus
`LENGTH(s : STRING) RETURNS INTEGER`	Returns string length	`LENGTH("Happy Days")` -> `10`	Both
`MID(s : STRING, x : INTEGER, y : INTEGER) RETURNS STRING`	Returns y chars from position x	`MID("ABCDEFGH", 2, 3)` -> `"BCD"`	9618
`RIGHT(s : STRING, x : INTEGER) RETURNS STRING`	Returns rightmost x chars	`RIGHT("ABCDEFGH", 3)` -> `"FGH"`	9618
`LEFT(s : STRING, x : INTEGER) RETURNS STRING`	Returns leftmost x chars	`LEFT("CAMBRIDGE", 3)` -> `"CAM"`	0478
`SUBSTRING(s : STRING, x : INTEGER, y : INTEGER) RETURNS STRING`	Extracts y chars from position x	`SUBSTRING("HELLO", 2, 3)` -> `"ELL"`	0478
`LCASE(c : CHAR) RETURNS CHAR`	Returns lower-case equivalent	`LCASE('W')` -> `'w'`	Both
`UCASE(c : CHAR) RETURNS CHAR`	Returns upper-case equivalent	`UCASE('h')` -> `'H'`	Both
`&` (concatenation)	Joins two strings	`"Summer" & " Pudding"` -> `"Summer Pudding"`	Both

5.6 Numeric Functions

Function Signature	Description	Example	Syllabus
`INT(x : REAL) RETURNS INTEGER`	Returns integer part of x	`INT(27.5415)` -> `27`	Both
`RAND(x : INTEGER) RETURNS REAL`	Random real in range 0 to x (exclusive)	`RAND(87)` may return `35.43`	9618
`NUM_TO_STR(x) RETURNS STRING`	Converts number to string	`NUM_TO_STR(42)` -> `"42"`	0478
`STR_TO_NUM(s : STRING) RETURNS NUMERIC`	Parses string to number	`STR_TO_NUM("42")` -> `42`	0478
`ROUND(x : REAL, places : INTEGER) RETURNS REAL`	Rounds to the given number of decimal places	`ROUND(7.246, 2)` -> `7.25`	0478
`RANDOM() RETURNS REAL`	Random real between 0 and 1	`RANDOM()` may return `0.64`	0478