To run the examples in this chapter, you will need a recent C++ compiler that understands C++17. Although the examples are not complex enough to require the functionality of the new standard, the examples have been set up accordingly.

We recommend using any of the compilers listed here to run the examples:

• Linux: GCC 9 or newer, Clang 10 or newer
• Windows: MSVC 19 or newer or MinGW 9.0.0 or newer
• macOS: Apple Clang 10 or newer

  Note

  To try out any examples in this book, we have provided a ready-made Docker container that contains all the requirements.

  You can find it at https://github.com/PacktPublishing/CMake-Best-Practices.

CMake is open source and available on many platforms. It is also compiler-independent, making it a very strong tool when it comes to building and distributing cross-platform software. All these features make it a valuable tool for building software in a modern way – that is, by relying heavily on build automation and built-in quality gates.

CMake consists of three command-line tools:

• cmake: CMake itself, which is used to generate build instructions
• ctest: CMake's test utility, which is used to detect and run tests
• cpack: CMake's packaging tool, which is used to pack software into convenient installers, such as deb, RPM, and self-extracting installers

There are also two interactive tools:

• cmake-gui: A GUI frontend to help with configuring projects
• ccmake: An interactive terminal UI for configuring CMake

cmake-gui can be used to conveniently configure a CMake build and select the compiler to be used:

Figure 1.1 – cmake-gui after configuring a project

If you're working on the console but still want to have an interactive configuration of CMake, then ccmake is the right tool. While not as convenient as cmake-gui, it offers the same functionality. This is especially useful when you must configure CMake remotely over an ssh shell or similar:

Figure 1.2 – Configuring a project using ccmake

The advantage of CMake over a regular build system is manyfold. First, there is the cross-platform aspect. With CMake, it is much easier to create build instructions for a variety of compilers and platforms without the need to know the specifics of the respective build system in depth.

Then, there is CMake's ability to discover system libraries and dependencies, which lessens the pain of locating the correct libraries for building a piece of software considerably. An additional bonus is that CMake integrates nicely with package managers such as Conan and vcpkg.

It is not just the ability to build software for multiple platforms, but also its native support for testing, installing, and packaging software that makes CMake a much better candidate for building software than just a single build system. Being able to define everything from building and over-testing to packaging at a single point helps tremendously with maintaining projects in the long run.

The fact that CMake itself has very few dependencies on the system and can run on the command line without user interaction makes it very suitable for build system automatization in CI/CD pipelines.

Now that we've covered briefly what CMake can do, let's learn how to install CMake.

CMake is freely available to download from https://cmake.org/download/. It is available as either a precompiled binary or as source code. For most use cases, the precompiled binary is fully sufficient, but since CMake itself has very few dependencies, building a version is also possible.

Any major Linux distribution offers CMake over its package repositories. Although the pre-packaged versions of CMake are not usually the latest releases, these installations are often sufficient to use if the system is regularly updated.

Note

The minimum version of CMake to use with the examples in this book is 3.21. We recommend that you download the appropriate version of CMake manually to ensure that you get the correct version.

Building CMake from source

CMake is written in C++ and uses Make to build itself. Building CMake from scratch is possible, but for most use cases, using the binary downloads will do just fine.

After downloading the source package from https://cmake.org/download/, extract it to a folder and run the following command:

./configure make

If you want to build cmake-gui as well, configure it with the --qt-gui option. This requires Qt to be installed. Configuring will take a while, but once it's succeeded, CMake can be installed using the following command:

make install

To test whether the installation was successful, you can execute the following command:

cmake --version

This will print out the version of CMake, like this:

cmake version 3.21.2
CMake suite maintained and supported by Kitware (kitware.com/
cmake).