Lecture 9 Summary: Function Fundamentals

1. The Importance of Functions

• Modularity: Functions allow programmers to divide a large program into smaller, manageable parts.
• Code Reuse: They prevent the need to repeat the same piece of code in multiple places.
• Readability: Programs become cleaner and easier to understand when logic is organized into functions.

2. Internal vs. External Functions

• Internal (User-Defined): Created by the programmer to solve specific tasks.
• External (Built-in): Functions grouped in specialized libraries like <iostream>, <cmath>, or <cstdlib>.

3. Function Workflow

• Include Statement: Necessary libraries must be included first.
• Function Prototype (Declaration): Written before main() to tell the compiler the function's name, return type, and parameters.
• Main Function: Where the program starts and where functions are typically "Called".
• Function Definition: The actual code block (body) that executes the task.

4. Syntax and Components

• Return Type: Indicates the type of value returned (e.g., int, double). Use void if the function returns nothing.
• Parameters: Placeholders defined in the function header to receive data.
• Arguments: The actual values passed to the function during the call.
• Return Statement: Used to send a result back to the caller.