Key takeaways:
CMake simplifies building complex C++ projects across platforms.
Ensure CMake is installed before starting.
CMakeLists.txtconfigures project settings, C++ standard, and source files.Create a separate
build/directory to keep build files separate.Use
cmake ..to generate platform-specific build files and compile withmake.Run the built executable from the terminal.
CMake is a powerful
Before diving into the build process, ensure CMake is installed on your system. You can install it using your package manager or download it from the official CMake website.
Organize your project with a clear directory structure. This will make things simpler when creating your CMakeLists.txt file later. Consider a project directory with the following components:
project-root/├── include/│ └── some-header.h├── src/│ └── main.cpp└── CMakeLists.txt
The include/ directory contains the header files, while the src/ directory holds the source code, such as main.cpp. A well-organized structure like this makes it easier to manage files as your project scales. It also helps in quickly locating resources, improving maintainability. With this structure, users should feel more confident handling even complex builds, and future collaborations or extensions to the project will be smoother.
CMakeLists.txtNow, let’s create a simple CMakeLists.txt file in the project root to configure the build:
cmake_minimum_required(VERSION 3.15)project(MyProject)# Set C++ standardset(CMAKE_CXX_STANDARD 11)# Include directoriesinclude_directories(include)# Add source filesadd_executable(output src/main.cpp)
In the CMakeLists.txt file:
Line 1: Specifies the CMake version needed.
Line 2: Names your project (here it’s MyProject).
Line 5: Sets the C++ standard to 17.
Line 8: Tells the compiler where to find header files.
Line 11: Defines the executable and its source file.
By configuring this correctly, you ensure CMake can efficiently manage your project’s build process.
Create a build directory to keep
mkdir buildcd build
Run CMake from within the build directory to generate platform-specific build system files:
cmake ..
Now, use the generated build system (e.g., Makefile) to compile the project:
On Unix-based systems:
make
On Windows:
cmake --build . --config Release
Now that the project has been built, simply run the generated executable in the terminal:
./output
Let’s consider a simple example using the directory structure and configuration above. We can test the commands we’ve covered, such as setting up the CMakeLists.txt, configuring the build system, and building the project.
Here’s how the flow works:
Create the directory structure.
Write the example C++ code in main.cpp.
Configure the build using CMake.
Build the project using the appropriate commands for your system.
This example will be a Unix-based system. Click “Run” and execute the above commands in the widget below:
cmake_minimum_required(VERSION 3.15) project(MyProject) # Set C++ standard set(CMAKE_CXX_STANDARD 11) # Include directories include_directories(include) # Add source files add_executable(output src/main.cpp)
Building a project with CMake involves creating a CMakeLists.txt file, configuring it appropriately, and then using CMake to generate build system files. This separation allows for platform-independent builds and easy maintenance of complex projects.
The provided example demonstrates a minimal project setup, but CMake is highly versatile, accommodating various project structures and configurations. As projects grow in complexity, additional CMake features can be leveraged to handle dependencies, testing, and more.
CMake provides a robust and flexible solution for building software projects, empowering developers to manage complex build processes with ease.
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