Interactive Computer Science Tutoring

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C Functions - The Recipe Kitchen

Master function definition, parameters, and return values through cooking metaphors

📚 Building on Variables

Variable Memory: Variables live in memory with specific addresses and types.

Today's Goal: Learn how functions organize code into reusable "recipes" with ingredients (parameters).

🤔 Function Behavior Prediction

Before we explore functions, predict: When you call add_numbers(5, 10), what happens to the original numbers?

👨‍🍳 Welcome to the Code Kitchen!

Think of functions as recipes in a kitchen. Each recipe has:

📋 Recipe Name
The function name (like "add_numbers")

🥕 Ingredients
Parameters that get copied into the kitchen

🍰 Final Dish
The return value served back to the caller

🔑 Key Insight: When you give ingredients to a chef, they make copies to work with. Your original ingredients in the pantry stay unchanged!

Function Definition

Learn how to create recipes (functions) in your code kitchen

Parameters & Arguments

Pass ingredients (arguments) to your recipe functions

Return Values

Functions can return finished dishes (values) to the caller

Function Calling

Execute your recipes and see the cooking process in action

Function Definition - Creating Recipes

Understand function definition syntax

Grasp parameter passing (pass-by-value)

Master return values and types

Execute and trace function calls

⚡ Function Challenge

What happens to the original variable when you pass it to a function in C?

🐛 Function Debugging Detective

Debug these common function mistakes! Can you spot what's wrong?

int multiply(int x, int y) {
    x * y;
}

Error: Missing return statement

💡 Show Explanation

Functions that return a value must use the 'return' keyword to send the result back to the caller.

✅ Show Fix

int multiply(int x, int y) {
    return x * y;
}

void print_double(int n) {
    return n * 2;
}

Error: void function cannot return a value

💡 Show Explanation

Void functions don't return values. Either change to 'int' return type or remove the return statement.

✅ Show Fix

int print_double(int n) {
    return n * 2;
}

📊 Function Confidence Check

Writing function definitions correctly