WK2: Procedural Programming and Control Structures in Python (Session 1)

• Programming
• Higher Education (degree)

Welcome

Procedural Programming and Control Structures in Python

Week 2

Module Lecturer: Dr Raghav Kovvuri

Email: [e-mail]

Retrospect: Flowcharts

• A flowchart is a graphical representation of an algorithm or process

Key components:

• Oval: Start/End
• Rectangle: Process/Action
• Diamond: Decision
• Parallelogram: Input/Output
• Arrows: Flow direction

Benefits:

• Visual clarity of process flow
• Easy to understand and communicate
• Helpful in identifying bottlenecks

Example: Flow Chart

Retrospect: Pseudocode Pseudocode 

• Pseudocode is a informal, high-level description of an algorithm

Key Components

• Input/Output statements
• Assignment operations
• Conditional statements (IF-THEN-ELSE)
• Loops (WHILE, FOR)
• Function calls

Characteristics

• Written in a mixture of natural language and simple programming constructs
• Not tied to any specific programming language
• Focuses on logic rather than syntax

Example: Pseudocode

Procedural Programming (1)

Definition: Programming paradigm based on the concept of procedure calls

Key Characteristics:

• Sequence: Instructions executed in order
• Selection: Decision making (if-else statements)
• Iteration: Repetition of a process (loops)
• Modularity: Breaking code into reusable procedures or functions

Comparison with Other Paradigms:

• Object-Oriented: Focuses on objects that contain data and code
• Functional: Emphasizes the application of functions to solve problems

Procedural Programming (2)

Advantages:

• Simplicity and ease of implementation
• Code reusability through functions
• Straightforward flow of control

Python Functions

Basics and Parameters

1. Defining Functions:

Function Parameters 

• Positional arguments: Order matters

• Keyword arguments: Order doesn't matters

• Default parameters:

Return Values

• Single return value:

• Multiple return value:

Scope and Lifetime of Variables (1)

• Local variables: Defined inside a function, only accessible within that function 

• Global variables: Defined outside functions, accessible throughout the program

Lifetime of Variables (2) 

• The global keyword: Used to modify global variables within a function

Control Structures

Conditional Statements

• If Statements:

• If-Else Statements:

Conditional Statements (2)

• Nested If Statements

• If-Elif-Else Statements

Conditional Statements(3)

• Ternary Operator:

Control Structures 

Loops (1)

'For' Loop:

• Iterating over a range:

• Iterating over a list:

Loops (2)

• 'While' Loop

• Nested Loops

Loops (3)

Loop Control Statements:

break: Exit the loop prematurely

continue: Skip the rest of the current iteration

else clause in loops: Executed when loop completes normally

Practical Exercise

Simple Calculator

Task: Create a simple calculator that can perform basic arithmetic operations.

• Download Simple Calculator.py from Canvas and comment and run the code accordingly

Key Takeaways

Procedural Programming Fundamentals:

• Sequence, Selection, Iteration
• Modularity through functions

Python Implementation:

• Functions: Definition, parameters, return values, scope
• Control Structures: Conditional statements, loops

Importance of Algorithms:

• Flowcharts and pseudocode for planning
• Translating algorithms into code