Call stack behavior - Mini Project: Build & Apply

Call Stack Behavior

📖 Scenario: Imagine you are baking a layered cake. Each layer must be added one after another, and you can only add the next layer after finishing the previous one. This is similar to how the call stack works in programming, where functions wait for others to finish before continuing.

🎯 Goal: You will write a simple C program with three functions calling each other. You will observe how the call stack works by printing messages when entering and exiting each function.

📋 What You'll Learn

Create three functions named first, second, and third.

Each function should print a message when it starts and when it ends.

The first function should call second, and second should call third.

The main function should call first.

Print the messages exactly as specified.

💡 Why This Matters

🌍 Real World

Understanding call stack behavior helps debug programs and understand how function calls work in real applications like games, web servers, and calculators.

💼 Career

Many programming jobs require understanding how functions call each other and how the call stack manages these calls to write efficient and bug-free code.

1

Create the third function

Write a function called third that prints "Entering third" when it starts and "Exiting third" when it ends.

C

#include 

void third() {
    // Your code here
}

int main() {
    return 0;
}

Need a hint?

Use printf to print messages inside the third function.

2

Create the second function that calls third

Write a function called second that prints "Entering second" when it starts, calls the third function, then prints "Exiting second" when it ends.

C

#include 

void third() {
    printf("Entering third\n");
    printf("Exiting third\n");
}

void second() {
    // Your code here
}

int main() {
    return 0;
}

Need a hint?

Call the third() function between the two printf statements.

3

Create the first function that calls second

Write a function called first that prints "Entering first" when it starts, calls the second function, then prints "Exiting first" when it ends.

C

#include 

void third() {
    printf("Entering third\n");
    printf("Exiting third\n");
}

void second() {
    printf("Entering second\n");
    third();
    printf("Exiting second\n");
}

void first() {
    // Your code here
}

int main() {
    return 0;
}

Need a hint?

Call the second() function between the two printf statements.

4

Call first from main and print the output

In the main function, call the first function. Then compile and run the program to see the messages showing the call stack behavior.

C

#include 

void third() {
    printf("Entering third\n");
    printf("Exiting third\n");
}

void second() {
    printf("Entering second\n");
    third();
    printf("Exiting second\n");
}

void first() {
    printf("Entering first\n");
    second();
    printf("Exiting first\n");
}

int main() {
    // Your code here
}

Need a hint?

Call first() inside main() and run the program to see the order of messages.