Chapter 29
Iterators, and What range-for Becomes
begin, end, and lambdas properly.
Part 2
This chapter needs a key
Chapter 13 told you to write v.begin(), v.end() and not ask questions. This is the answer, and it turns out range-for, std::find and std::sort are all the same idea wearing different clothes.
You'll build: Take the loop apart. Walk a container four ways, then write the same sort with a function and with a lambda.
Part 1, chapters 0 to 21, is free and always will be.