When I was learning programming I had no internet, no books outside of library, nobody to ask for days.
I remember vividly having spent days trying to figure out how to use the stdlib qsort, and not being able to.
E.g.
void qsort(void* base, size_t nmemb, size_t size, int (compar)(const void , const void* ));
And surely if you bought a C compiler, you would have gotten a manual or two with it? Documentation from the pre-Internet age tended to be much better than today.
Also I don't know if it came with manual but my English wasn't good enough to read them anyways.
qsort(base, nel, width, compar)
char *base;
int (*compar)();