11.3 Structured Programming

Structured programming is a fundamental paradigm in computer science that emphasizes the use of control flow structures to create well-organized and readable code. It avoids the use of unstructured constructs like `GOTO` statements, which can lead to complex and difficult-to-debug programs. The core principles of structured programming are sequences, selections (if-then-else), and iterations (loops).

Key Concepts

• Sequence: Instructions are executed in a linear order.
• Selection: Allows for different blocks of code to be executed based on a condition (e.g., `if`, `else if`, `else`).
• Iteration: Enables the repetition of a block of code (e.g., `for`, `while`, `repeat-until`).

PseudoCode: An Introduction

PseudoCode is an informal way of describing the logic of a program. It uses a combination of natural language and programming-like syntax to outline the steps involved. It's not intended to be directly executed by a computer but serves as a blueprint for translating into a specific programming language.

Basic PseudoCode Constructs

Construct	Description	Example
Assignment	Assigns a value to a variable.	x = 10
Conditional Statement (if-then-else)	Executes different blocks of code based on a condition.	if (condition) then // Code to execute if condition is true else // Code to execute if condition is false end if
Loop (For loop)	Repeats a block of code a specified number of times.	for i = start to end do // Code to execute in each iteration end for
Loop (While loop)	Repeats a block of code as long as a condition is true.	while (condition) do // Code to execute while condition is true end while
Function/Procedure Definition	Defines a reusable block of code.	function calculateArea(length, width) area = length * width return area end function

Writing Efficient PseudoCode

To write efficient pseudoCode, consider the following:

• Clarity: Use clear and concise language.
• Modularity: Break down complex tasks into smaller, manageable functions or procedures.
• Avoid Redundancy: Don't repeat the same code blocks unnecessarily. Use loops or functions instead.
• Indentation: Use indentation to clearly show the structure of the code (e.g., for nested blocks).

Example: Calculating the Area of a Rectangle

Here's an example of pseudoCode to calculate the area of a rectangle:

function calculateRectangleArea(length, width) area = length * width return area end function // Main program get length get width rectangleArea = calculateRectangleArea(length, width) display "The area of the rectangle is: " + rectangleArea

Practice

Practice writing pseudoCode for various problems. Start with simple tasks and gradually increase the complexity. This will help you develop a strong understanding of structured programming principles.