Before I discovered 'Make', I thought of making a command line tool that would compile all my C++ assignment files in 1 command. And only compile the ones that had any changes made to them in order to make it faster ⚡. So, I thought of using the SHA1 hashing algorithm to calculate the hashes of all files in my assignments directory and save them in a database file. Then only compile the ones with changes.
Soon after I (somehow) implemented the SHA1 algorithm from the FIPS PUB 180-1 (https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub180-1.pdf) paper, I discovered 'Make' and ditched the project. But hey, even if I didn't finish it, it still was my first (kinda successful) project in C++ :)