CMake Cookbook

When invoking the CMake project command with a VERSION argument, CMake will set the PROJECT_VERSION_MAJOR, PROJECT_VERSION_MINOR, and PROJECT_VERSION_PATCH for our project. The key command in this recipe is configure_file, which takes an input file (in this case, version.h.in) and generates an output file (in this case, generated/version.h) by expanding all placeholders between @ to their corresponding CMake variables. It replaces @PROJECT_VERSION_MAJOR@ with 2, and so on. With the keyword @ONLY, we limit configure_file to only expand @variables@, but to not touch ${variables}. The latter form is not used in version.h.in, but they frequently appear when configuring a shell script using CMake.

The generated header file can be included in our example code, and the version information is available to be printed:

$ mkdir -p build
$ cd build
$ cmake ..
$ cmake --build .
$ ./example

This is output from code v2.0.1
Major version number: 2
Minor version number: 0
Hello CMake world!

CMake understands version numbers given in the format X.Y.Z.t, and will set the variables PROJECT_VERSION and <project-name>_VERSION to the passed value. In addition, the PROJECT_VERSION_MAJOR (<project-name>_VERSION_MAJOR), PROJECT_VERSION_MINOR (<project-name>_VERSION_MINOR), PROJECT_VERSION_PATCH (<project-name>_VERSION_PATCH), and PROJECT_VERSION_TWEAK (<project-name>_VERSION_TWEAK), will be set to X, Y, Z, and t, respectively.

Table of Contents for
CMake Cookbook

How it works

Table of Contents for CMake Cookbook

Table of Contents for
CMake Cookbook