A calculator that allows you to input a network class or IP address and calculates the subnet mask
(Might work on mac too idk. On Windows, you'll probably have to generate a VS project using CMake - No idea how you'd do that though)
In the repo folder (same folder as CMakeLists.txt) make a directory 'build' and navigate to it.
Then run these commands:
cmake ..
make
And to run:
./SubnetMasksExe