Functions and Procedures

Overview

Functions and procedures are key components of modular programming. They allow developers to organise code into smaller, reusable blocks. Although both serve similar purposes, there are important differences in how they operate and are used.

Understanding how to define, use, and trace functions and procedures is essential for writing efficient, modular, and maintainable code.

What are Functions?

• Definition: A function is a block of code that performs a specific task and returns a value.
• Purpose: Used when the result of the operation needs to be used elsewhere in the program.

FUNCTION calculateArea(radius)
    RETURN 3.14 * radius * radius
END FUNCTION

def calculate_area(radius):
    return 3.14 * radius * radius

What are Procedures?

• Definition: A procedure is a block of code that performs a specific task but does not return a value.
• Purpose: Used when the task modifies data, interacts with the user or produces an output without needing to return a value.

PROCEDURE displayMessage()
    PRINT "Hello, World!"
END PROCEDURE

def display_message():
    print("Hello, World!")

Differences Between Functions and Procedures

Using Functions and Procedures Together

Functions and procedures can work together to build modular, efficient programs.

FUNCTION calculateAverage(marks)
    total = 0
    FOR EACH mark IN marks
        total = total + mark
    ENDFOR
    RETURN total / LENGTH(marks)
END FUNCTION

PROCEDURE displayResult(name, average)
    PRINT "Student:", name
    PRINT "Average Mark:", average
END PROCEDURE

MAIN
    marks = [85, 90, 78]
    average = calculateAverage(marks)
    displayResult("Alice", average)
END MAIN

Tracing Code with Functions and Procedures

FUNCTION square(x)
    RETURN x * x
END FUNCTION

PROCEDURE printSquare(value)
    result = square(value)
    PRINT result
END PROCEDURE

MAIN
    printSquare(3)
END MAIN

Benefits of Using Functions and Procedures

1. Code Reusability: Functions and procedures can be called multiple times, reducing code duplication.
2. Improved Readability: By breaking the program into smaller sections, modular code is easier to understand and maintain.
3. Simplified Testing and Debugging: Individual functions and procedures can be tested independently.
4. Collaborative Development: Different team members can work on different functions or procedures.

Practical Applications of Functions and Procedures

1. Mathematical Calculations: Functions like calculateArea() or findMaximum() can handle repetitive calculations.
2. User Interaction: Procedures like displayMenu() or printErrorMessage() manage user interactions.
3. File Handling: Procedures can open, read, write, or close files while functions return specific data.

Note Summary