The CMake Configuration

Write the Top-Level CMake File

Start by creating the project-wide CMakeLists.txt in the root directory. This file defines the overall project and registers the subdirectories that contain the library and the application.

Create and open the file:
```
$ nano CMakeLists.txt
```

Add the following content:

<project>/CMakeLists.txt

  cmake_minimum_required(VERSION 3.28)
  project(SignalBoardProject LANGUAGES CXX)

  add_subdirectory(erbsland-cpp-color-term)
  add_subdirectory(signal-board)

The library directory is added first so its targets are available when the application is configured.

Write the Application CMake File

Next, create the CMake configuration for the tutorial application itself.

Create and open the file:
```
$ nano signal-board/CMakeLists.txt
```

Add the following content:

<project>/signal-board/CMakeLists.txt

  cmake_minimum_required(VERSION 3.28)
  project(SignalBoard LANGUAGES CXX)

  add_executable(signal-board
      src/main.cpp
  )

  target_compile_features(signal-board PRIVATE cxx_std_20)
  target_link_libraries(signal-board PRIVATE erbsland-color-term)

This configuration creates the executable and links it against the erbsland-color-term library that was registered in the top-level build.

Important Details

A few important lines in this configuration are worth highlighting:

add_subdirectory(erbsland-cpp-color-term) registers the library and makes its targets available to the rest of the build.
target_compile_features(... cxx_std_20) enables the required C++20 language features for the application.
target_link_libraries(... erbsland-color-term) links the executable with the terminal rendering library.

The Current Project State

Your directory should now look like this:

signal-board-project
    ├── erbsland-cpp-color-term
    ├── signal-board
    │   ├── src
    │   └── CMakeLists.txt         # [new] Application build file
    └── CMakeLists.txt             # [new] Top-level build file

Write a Minimal Main Function →