Question

I’m having a hard time conceptualizing c++ sets, actually sets in general.

What are they? How are they useful?

Answer 1

Don’t feel bad if you have trouble understanding sets in general. Most of a degree in mathematics is spent coming to terms with set theory:

http://en.wikipedia.org/wiki/Set_theory

Think of a set as a collection of unique, unordered objects. In many ways it looks like a list:

{ 1, 2, 3, 4 }

but order is unimportant:

{ 4, 3, 2, 1} = { 1, 2, 3, 4}

and repetitions are ignored:

{ 1, 1, 2, 3, 4 } = { 1, 2, 3, 4}

A C++ set is an implementation of this mathematical object, with the odd feature that is is sorted internally. But this is just a detail of implementation, and is not relevant to understanding the data structure. The sorting is just for speed.