CMake basics
- C++ course
- Advanced
- Lesson 43/83
- 5 min
Learn build configuration with CMake.
What is CMake?
CMake is a build system generator for C++ projects. It does not compile directly; instead it produces Makefiles or Ninja files that build the project. It is cross-platform: the same build file works on Linux, macOS and Windows.
Every CMake project has a CMakeLists.txt at its root. The three basic commands are: cmake_minimum_required(VERSION 3.20) for the minimum version, project(MyApp) for the project name, and add_executable(myapp main.cpp) to define an executable target. After writing this file you run cmake . to generate build files.
project and add_executable
The project(MyApp) command names the project and sets the default language (C/C++). You can specify the language explicitly with project(MyApp LANGUAGES CXX). This command also defines the PROJECT_NAME variable.
The add_executable(myapp main.cpp) command defines an executable target named myapp. You can list source files one by one: add_executable(myapp main.cpp utils.cpp). The target name usually matches the project name. CMake compiles this target and produces the executable.
Practice Write your first CMakeLists.txt
Write a CMakeLists.txt. Define the version with cmake_minimum_required(VERSION 3.20), the project name with project(MyApp), and the executable target with add_executable(myapp main.cpp).
Starter code
# CMakeLists.txt
# Add the cmake commands hereSample solution
cmake_minimum_required(VERSION 3.20)
project(MyApp)
add_executable(myapp main.cpp)Expected output
Configuration ready
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does CMake produce?
- An executable directly
- C++ source code
- Build files (Makefile or Ninja) Correct answer
- A class diagram
Explanation: CMake produces Make or Ninja build files; they compile the project.
2 Complete the version command
____(VERSION 3.20)cmake_minimum_required(VERSION 3.20)Explanation: cmake_minimum_required sets the minimum CMake version.
3 Match the command to its role
| Term | Meaning |
|---|---|
cmake_minimum_required |
Minimum version |
project(MyApp) |
Sets project name |
add_executable |
Executable target |
CMakeLists.txt |
Build file |