Essential CMake Commands for Building C/C++ Projects

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CMake: The Comprehensive Guide to Managing and Building C++ Projects (From Basics to Mastery)

What Is CMake?

CMake is a cross-platform build system generator. It doesn’t compile your code directly—instead, it generates native build scripts (e.g., Makefiles, Ninja, or Visual Studio projects) that do. It has become the de facto standard for configuring, managing, and building C/C++ projects of all sizes.

1. Minimal CMakeLists.txt for C++

cmake_minimum_required(VERSION 3.14)
project(MyProject LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(MyApp src/main.cpp)

This sets up a minimal modern C++ project targeting C++20.

2. Most Important Modern CMake Commands

project()

Declares the project name and programming languages:

project(MyProject LANGUAGES C CXX)

set()

Defines variables, such as the C++ standard:

set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable()

Defines the final binary and its source files:

add_executable(app src/main.cpp src/utils.cpp)

add_library()

Defines a static or shared library:

add_library(mylib STATIC src/mylib.cpp)

target_include_directories()

Adds header search paths for a target:

target_include_directories(app PRIVATE include/)

target_link_libraries()

Links libraries to an executable or another library:

target_link_libraries(app PRIVATE mylib)

file(GLOB ...)

Collects multiple source files automatically:

file(GLOB SOURCES "src/*.cpp")
add_executable(app ${SOURCES})

Note: While convenient in small projects, file(GLOB ...) is discouraged for large projects due to poor dependency tracking. Explicit listing is preferred in production environments.

3. Building the Project with CMake

In the terminal:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
cmake --build .

CMAKE_BUILD_TYPE can be Release, Debug, RelWithDebInfo, etc.

4. Complete Example: Clean Project Structure

Directory layout:

MyProject/
 ├── src/
 │     ├── main.cpp
 │     └── utils.cpp
 ├── include/
 │     └── utils.h
 └── CMakeLists.txt

CMakeLists.txt:

xxxxxxxxxx
cmake_minimum_required(VERSION 3.14)
project(MyProject LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

file(GLOB SOURCES "src/*.cpp")

add_executable(MyApp ${SOURCES})

target_include_directories(MyApp PRIVATE include)

5. Key Practices for Modern CMake

• Use target_\* commands exclusively (target_link_libraries, target_include_directories, etc.) to isolate dependencies cleanly per target.

• Avoid global variables like include_directories() or link_directories()—these are outdated and break encapsulation.

• Use modern CMake (3.14+) and newer standards like C++20 or C++23.

• Split large projects into subdirectories using add_subdirectory() and manage libraries modularly.

• Use find_package() for integrating external libraries with CMake’s native support (e.g., Boost, SDL, Qt).

Final Note: Don’t Fear CMake

Many developers initially struggle with CMake because it feels like “just another language.” But:

• It’s easier than it looks—especially with modern patterns.

• You’ll gain complete control over your build process and dependencies.

• Mastering it makes you a stronger C++ developer, especially when dealing with larger or cross-platform projects.