Week-6-1

Introduction to Functions

• Functions are defined using the def keyword followed by a function name, with parentheses and a colon.

• The statements that make up the function's body follow and are intended to group together a number of statements for convenience.

Function Definition and Purpose

• Functions enable code organization by grouping statements into a callable unit.

• Example: A function can be created to calculate the area of a pizza:

  • Use Pi, diameter, and radius (calculated as diameter divided by 2).

  • The area is computed using the formula: Area = Pi * r^2 (where r is the radius).

  • The function returns the computed area.

Function Call and Execution

• When a function is called, the control transfers to the function body, executing statements until a return is reached.

• The returned value replaces the function call in the original print statement.

• Example Explanation:

  • The function call outputs a formatted statement about the pizza's area based on calculations.

Example Function: Squaring a Number

• A simple function can compute the square of a given number:

  • Function definition includes an argument (e.g., num2square).

  • When called with a specific number (e.g., 7), it computes and returns the square (7 x 7 = 49).

  • Result (49) can be stored in a variable and printed.

More Complex Function: Calculating Pizza Volume

• Function can also calculate pizza volume:

  • Requires parameters for pizza diameter and height.

  • Volume is computed as: Volume = Area * Height (area calculated as before).

• Example call with diameter (12) and height (0.3), returning the calculated volume.

Reusability of Functions

• Functions can be reused by calling them multiple times with different arguments; different computations can occur each time.

• Example: Different diameter and height values for pizza volume calculation.

Void Functions

• Functions that perform tasks without returning values are known as void functions.

• Example: A function to print summaries of orders (e.g., order ID, items, price) without calculating any results.

• Helps organize print statements and reduce redundancy.

Dynamic Typing and Polymorphism

• Dynamic typing: Variable types are determined at runtime based on assigned values.

  • Example: An add function can add integers, doubles, or concatenate strings based on the provided arguments.

• Polymorphism allows the same operator (e.g., +) to perform different operations based on operand types.

Organizing Code with Functions

• Functions improve code readability by grouping related statements, making maintenance easier.

• Comparison of function-based code versus non-function-based code highlights the benefits of modularity and maintainability.

Modular Development

• Breaking a program into independent modules enhances testing and efficiency during development.

• Allows systematic integration of functions as programming progresses.

Mathematical Functions Example

• Function to convert measurements (e.g., US sizes to centimeters).

• Execution flow demonstrates the calling of functions and the return of computed values.

• Example of modular functions where functions can call other functions for calculation and organization.

Incremental Development

• Developing programs incrementally by writing, testing, and refining code in small parts.

• Function stubs: defining function names without all logic to facilitate incremental testing.

Error Handling for Unimplemented Functions

• Employing raise NotImplementedError ensures that if a function isn't implemented, the program stops execution and alerts the developer.

• This minimizes the risk of forgetting to complete function implementations.

Example Usage of Functions in Real Applications

• Calculating eBay fees based on sale price using functions for different price brackets.

• Functions can include conditional logic and loops to accomplish various tasks, similar to standard programming constructs.