This (a hash table) is a basic vocabulary type, and it's only barely understandable that C doesn't provide one given when it was invented. The hash table which people are likely to knock together this way in C isn't very good, which makes sense - but if the C library provided one then the effort to do it well only needs to happen once.

This isn't like say, Bloom filters where most people don't need one. It's like sort, which I notice C does provide in its standard library.