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CHAPTER 11: PROGRAMMING FUNDAMENTALS

11.1 PROGRAMMING BASICS

11.1.1 Variables and Constants

Variable Declaration:

<TEXT>

DECLARE variable : TYPE

Constant Declaration:

<TEXT>

CONSTANT name ← value

Assignment:

<TEXT>

variable ← value

11.1.2 Input/Output

Input:

<TEXT>

INPUT variable

Output:

<TEXT>

OUTPUT "message", variable

11.1.3 Arithmetic Operators

Operator Description
+ Addition
- Subtraction
* Multiplication
/ Division
DIV Integer division
MOD Remainder

11.1.4 Logical Operators

Operator Description
AND Both true
OR Either true
NOT Negation

11.2 CONSTRUCTS

11.2.1 Selection Statements

IF Statement:

<TEXT>

IF condition THEN
statements
ELSE
statements
END IF

Nested IF:

<TEXT>

IF condition1 THEN
IF condition2 THEN
statements
ELSE
statements
END IF
ELSE
statements
END IF

CASE Statement:

<TEXT>

CASE OF variable
value1 : statement
value2 : statement
OTHERWISE : statement
END CASE

11.2.2 Loop Structures

Count-Controlled (FOR):

<TEXT>

FOR counter ← start TO end
statements
NEXT counter

Pre-Condition (WHILE):

<TEXT>

WHILE condition
statements
END WHILE

Post-Condition (REPEAT):

<TEXT>

REPEAT
statements
UNTIL condition

Choice of Loop:

  • FOR: When number of iterations known
  • WHILE: When condition checked before first iteration
  • REPEAT: When condition checked after at least one iteration

11.3 STRUCTURED PROGRAMMING

11.3.1 Procedures

Definition: A reusable block of code that performs a specific task.

Declaration:

<TEXT>

PROCEDURE name(parameter1, parameter2)
statements
END PROCEDURE

Call:

<TEXT>

CALL name(argument1, argument2)

Parameters:

  • Passed by value: Copy of data passed
  • Passed by reference: Actual data passed (can be modified)

11.3.2 Functions

Definition: Returns a value; used in expressions.

Declaration:

<TEXT>

FUNCTION name(parameter) RETURN type
statements
RETURN value
END FUNCTION

Use:

<TEXT>

result ← name(arguments)
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