Code organization with functions in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of function call with parameters

What will be printed on the Serial Monitor when this Arduino code runs?

Arduino

void setup() {
  Serial.begin(9600);
  printSum(5, 3);
}

void loop() {}

void printSum(int a, int b) {
  Serial.println(a + b);
}

A Error: missing return type

B 8

C 53

D 0

💡 Hint

Remember that Serial.println prints the value passed to it.

The function printSum adds the two numbers and prints the result. 5 + 3 = 8.

🧠 Conceptual

intermediate

Purpose of the setup() function

What is the main purpose of the setup() function in an Arduino sketch?

A To run code repeatedly in a loop

B To define custom functions

C To declare global variables

D To run code once at the start of the program

💡 Hint

Think about what happens when the Arduino first turns on.

The setup() function runs once when the Arduino starts. It is used to initialize settings like pin modes or start serial communication.

🔧 Debug

advanced

Identify the error in function definition

What error will this Arduino code cause?

Arduino

void setup() {
  Serial.begin(9600);
  greet();
}

void loop() {}

void greet() {
  Serial.println("Hello, world!");
}

A SyntaxError: missing semicolon

B RuntimeError: greet not defined

C No error, prints 'Hello, world!'

D TypeError: wrong function return type

💡 Hint

Check punctuation at the end of each statement.

The function greet() is missing a semicolon after the Serial.println statement, causing a syntax error.

❓ Predict Output

advanced

Output of nested function calls

What will be printed on the Serial Monitor after running this code?

Arduino

void setup() {
  Serial.begin(9600);
  int result = multiply(add(2, 3), 4);
  Serial.println(result);
}

void loop() {}

int add(int x, int y) {
  return x + y;
}

int multiply(int a, int b) {
  return a * b;
}

A 20

B 14

C Error: multiply not defined

D 10

💡 Hint

Calculate the inner function first, then the outer.

The add(2, 3) returns 5. Then multiply(5, 4) returns 20, which is printed.

📝 Syntax

expert

Correct function prototype declaration

Which option correctly declares a function prototype for a function named blinkLED that takes an int parameter and returns nothing?

A blinkLED(void int duration);

B int blinkLED(int duration);

C void blinkLED(int duration);

D void blinkLED(duration int);

💡 Hint

Remember the syntax: return_type function_name(parameter_type parameter_name);

Option C correctly declares a function returning void, named blinkLED, with one int parameter named duration.