Chapter 2 Exercises¶

Work through these after reading Chapter 2. Try each one yourself before revealing the solution — you learn far more from an honest attempt than from reading a finished answer.

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

Both exercises are done in a real project and terminal — a CMakeLists.txt you write and a sequence of git commands you run. There is nothing to "run on Compiler Explorer"; the point is to do them for real on your own machine. (PlatformIO has no paper exercise — it needs a real board, so its practice belongs in the lab with hardware in hand.)

1. A project with two programs¶

Practises: CMake

You want to keep two of your Chapter 1 solutions — ex1.cpp and ex2.cpp — in a single project, each runnable on its own. Write a CMakeLists.txt that builds both as separate executables, uses C++20, and turns compiler warnings on for each.

Show solution

cmake_minimum_required(VERSION 3.16)
project(chapter1_solutions)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(ex1 ex1.cpp)
target_compile_options(ex1 PRIVATE -Wall -Wextra)

add_executable(ex2 ex2.cpp)
target_compile_options(ex2 PRIVATE -Wall -Wextra)

One add_executable per program gives you two entries in the run-configuration dropdown next to the green ▶ button — exactly the setup the Chapter 1 exercises suggested. CMAKE_CXX_STANDARD is set once near the top and applies to every target below it; warnings are switched on per target with target_compile_options. (You could instead apply them to everything with add_compile_options(-Wall -Wextra) before the targets — either is fine.)

2. Save your work with git¶

Practises: Version Control & Git

You have just created a new project folder containing a CMakeLists.txt and a main.cpp. Using git, (1) turn the folder into a repository, (2) save both files in a first commit with a sensible message, and then (3) start a branch called experiment to try a change without disturbing main. Write the commands in order.

Hint: a quick git status between steps is always a good way to check what git thinks is going on.

Show solution

git init                                  # turn the folder into a repo
git status                                # see what is untracked

git add CMakeLists.txt main.cpp           # stage both files
git commit -m "Initial project: builds Hello World"

git switch -c experiment                  # create + move onto a new branch

git add only stages the files — it marks them for the next snapshot. git commit is what actually records the snapshot, and its message says what this state is. git switch -c experiment creates the branch and moves you onto it in one step; anything you commit now lands on experiment, leaving main untouched until you choose to merge.