Computing Society: Session 3 Functions, Modules, and Data Structure

Session 3: Functions, Modular Programming, and Data Structures 🖥️💡

Total Duration: 60 minutes ⏳

Goal: Students will understand functions, modular programming, and basic data structures (lists, dictionaries, and arrays) in both Python 🐍 and C++ 💻. They will apply this knowledge by building modular programs and manipulating data structures.

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3.1 Understanding Functions 🔄

Time Allocation: 15 minutes ⏰

Concept Explanation:

• What are Functions? ⚙️
  A function is a block of organized, reusable code that performs a specific task. It helps break down programs into smaller, manageable sections, improving readability and reducing code repetition.

• Mechanism: 🔧
  When a function is called, the program jumps to that function, performs its task, and returns control to the calling code, optionally with a result (return value). Functions can accept inputs (arguments) and return outputs.

• In Python 🐍: Functions are defined using the def keyword, and return values with the return statement.

• In C++ 💻: Functions are defined with a return type, function name, and parameters. C++ functions specify the type of value they return.

Simple Task (for noobs) 👶

• Python 🐍: Write a function that takes a user’s name as input and prints a greeting.

  def greet(name):
      print(f"Hello, {name}!")
  
  greet("Alice")

• C++ 💻: Write a function that adds two numbers and returns the result.

  int add(int a, int b) {
      return a + b;
  }
  
  int result = add(3, 4);

Challenging Task (for advanced students) 🎯

• Factorial 🔢: Write a function that calculates the factorial of a number using recursion. $n!$
• Fibonacci ➰: Write a function that calculates the nth Fibonacci number using recursion.

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3.2 Modular Programming 🧩

Time Allocation: 15 minutes ⏰

Concept Explanation:

• What is Modular Programming? 🛠️
  Modular programming involves dividing a large program into smaller, manageable parts, often called functions or modules. Each module has a specific responsibility.

• Mechanism: 🛠️
  Functions are the fundamental building blocks of modular programming. A modular program is easier to debug 🐛, understand 👓, and maintain 🔧 because each function handles one specific aspect of the program.

• Clean Code 🧼: Keeping functions small, giving them meaningful names, and avoiding repeated code results in more readable and maintainable programs.

Simple Task (for noobs) 👶

• Python 🐍: Break down a program that calculates the area of a rectangle and a circle into separate functions.

  def area_rectangle(length, width):
      return length * width
  
  def area_circle(radius):
      return 3.14 * radius * radius
  
  print(area_rectangle(5, 4))
  print(area_circle(3))

• C++ 💻: Create a modular program where one function takes input, and another function calculates the square of a number.

  int get_input() {
      int x;
      cout << "Enter a number: ";
      cin >> x;
      return x;
  }
  
  int square(int x) {
      return x * x;
  }
  
  int num = get_input();
  cout << square(num);

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3.3 Working with Lists, Dictionaries, and Arrays 📚🔢

Time Allocation: 20 minutes ⏰

Concept Explanation:

• Lists (Python) 🐍:
  A list is a mutable, ordered collection of items. You can add ➕, remove ➖, and access elements by their index.

• Dictionaries (Python) 📖:
  A dictionary stores data as key-value pairs 🔑➡️, allowing fast lookup based on keys.

• Arrays (C++) 💻:
  Arrays are fixed-size collections of elements of the same type 🎲. They allow direct access to elements using their index.

• Mechanism: 🧠
  Lists and arrays store elements contiguously in memory, allowing fast access . Dictionaries use hashing to map keys to values for quick lookups 🔍.

Simple Task (for noobs) 👶

• Python (Lists & Dictionaries) 🐍: Create a list of names, add a new name to the list, and print the updated list. Then, create a dictionary with names and ages and access one of the values.

  names = ["Alice", "Bob", "Charlie"]
  names.append("David")
  print(names)
  
  ages = {"Alice": 25, "Bob": 30}
  print(ages["Bob"])

• C++ (Arrays) 💻: Create an array of integers, and print the elements using a loop.

  int arr[5] = {1, 2, 3, 4, 5};
  for (int i = 0; i < 5; i++) {
      cout << arr[i] << " ";
  }

Challenging Task (for advanced students) 🎯

• C++ (Arrays) 💻: Write a function to search for a number in a sorted array using binary search, with time complexity O(log n).
  Challenge: Can you do it using recursion? 🔄

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3.4 Hands-On Practice: Building Functions and Manipulating Data Structures 🛠️

Time Allocation: 10 minutes ⏰

Task:

• Noobs 👶: Write a function to calculate the sum of all elements in a list/array.
• Advanced 🎯: Write a program to implement a sorting algorithm (e.g., bubble sort, selection sort) for an array of numbers.
  Fast sort explained in 4 minutes 📺 fast sort (YouTube)