Function pointers

Store a function's address in a variable, pass callbacks to qsort with a comparator, and build a dispatch table that maps command names to C functions.

The skill

Pass functions around as values: write comparators for qsort, dispatch commands from a table and write your own function that takes a callback.

You make

A sorted leaderboard, a fixed race-time sort, a command table and a pick-the-best function that works on any type.