Also, qsort has a friend called bsearch.

If you look at the example here:

https://man7.org/linux/man-pages/man3/bsearch.3.html

First the array is sorted by name. Then bsearch is used for lookup. If the array had millions, using bsearch is a lot faster, because it doesn't have to search through the entire array. And the comparison function is the same.

Off: for learners, it would be an interesting exercise to find the missing features in bsearch(3)
For example the lack of user-parameter in callback (compare qsort(3) and qsort_r(3))