Chapter 1 Exercises

Work through these after reading Chapter 1. Try each one yourself before revealing the solution — you learn far more from an honest attempt, and the mistakes along the way, than from reading a finished program. Type the code into CLion and run it; do not just read it.

When you open a solution it appears blurred — click it once more to reveal it, so you do not see the answer by accident.

Where to put your code

Each exercise is its own small program with its own main(), and a CLion project runs one main() at a time. You have two options:

Simplest — keep one project open and replace the contents of main.cpp for each exercise. Run it, then paste in the next. (You lose the previous attempt, which is fine for quick practice.)

Keeps every exercise (recommended) — give each exercise its own file in a single project (ex1.cpp, ex2.cpp, …) and add one line per file to CMakeLists.txt:

add_executable(ex1 ex1.cpp)
add_executable(ex2 ex2.cpp)

Then choose which program to run from the run-configuration dropdown next to the green ▶ button. You do not need to understand CMakeLists.txt yet — CMake explains it in Chapter 2; for now, just copy the pattern.

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1. Introduce yourself

Practises: Basic Structure, Variables and Basic Types

Declare a std::string for your name and an int for your age (just like the chapter's int age = 25). Print one line:

My name is Ada and I am 36 years old.

Show solution

#include <iostream>
#include <string>

int main() {
    std::string name = "Ada";
    int age = 36;

    std::cout << "My name is " << name << " and I am " << age << " years old.\n";
}

Each variable gets the right type and is initialised as it is declared; << chains the pieces into one line.

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2. Average score

Practises: Operators and Expressions

You have three test scores: 7, 8, and 10. Print their average. Make sure it comes out as a decimal — 8.33…, not a truncated 8.

Show solution

#include <iostream>

int main() {
    int a = 7;
    int b = 8;
    int c = 10;

    double average = (a + b + c) / 3.0;   // 3.0 is a double, so the decimals are kept

    std::cout << "Average: " << average << "\n";
}

Divide by 3 (an int) and C++ does integer division — it throws the fraction away and you get 8. Writing 3.0 makes one side a double, so the decimals survive. That is the chapter's 10 / 3 rule in action.

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3. Sensor readings

Practises: Strings and Vectors

Store five sensor readings — 42, 17, 99, 8, 56 — in a std::vector<int>. Print how many there are, their average (as a decimal), and the largest.

Hint: loop over the vector to add up the values and track the biggest; readings.size() is the count.

Show solution

#include <iostream>
#include <vector>

int main() {
    std::vector<int> readings = {42, 17, 99, 8, 56};

    int sum = 0;
    int largest = readings[0];
    for (int r : readings) {
        sum += r;
        if (r > largest) {
            largest = r;
        }
    }

    double average = static_cast<double>(sum) / readings.size();

    std::cout << "Count:   " << readings.size() << "\n";
    std::cout << "Average: " << average << "\n";
    std::cout << "Largest: " << largest << "\n";
}

A range-based for visits every element: we add each to sum and keep the biggest seen so far. static_cast<double> keeps the division decimal (the integer-division rule again), and readings.size() gives the element count.

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4. Even or odd

Practises: Control Statements

Use a for loop to print the numbers 1 to 10, labelling each one even or odd.

Hint: a number is even when n % 2 == 0.

Show solution

#include <iostream>

int main() {
    for (int i = 1; i <= 10; ++i) {
        if (i % 2 == 0) {
            std::cout << i << " even\n";
        } else {
            std::cout << i << " odd\n";
        }
    }
}

A counter-based for loop like the one in the chapter, with an if/else inside it deciding what to print.

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5. Squares

Practises: Functions

Write a function int square(int n) that returns n * n (you saw this exact function in the chapter). Then use a for loop to print the squares of 1 through 5.

Show solution

#include <iostream>

int square(int n) {
    return n * n;
}

int main() {
    for (int i = 1; i <= 5; ++i) {
        std::cout << i << " squared is " << square(i) << "\n";
    }
}

A small function with one clear job, called from a loop. Defining square once and reusing it beats writing i * i everywhere.

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6. Traffic light

Practises: Enumerations

Define an enum class TrafficLight with Red, Amber, and Green. Write a function that prints the action for each — Stop, Get ready, Go — using a switch, and call it for all three.

Show solution

#include <iostream>

enum class TrafficLight {
    Red,
    Amber,
    Green
};

void act(TrafficLight light) {
    switch (light) {
        case TrafficLight::Red:   std::cout << "Stop\n";      break;
        case TrafficLight::Amber: std::cout << "Get ready\n"; break;
        case TrafficLight::Green: std::cout << "Go\n";        break;
    }
}

int main() {
    act(TrafficLight::Red);
    act(TrafficLight::Amber);
    act(TrafficLight::Green);
}

A fixed set of named values handled by a switch. With no default, the compiler warns you if you add a colour later and forget it here.