advantages of std::set vs vectors or maps

Question

This may be a stupid question, I am quite new to C++ and programming in general. I wish to understand the use of several STL containers and with that in mind, I was wondering what the advantages are of using std::set vs for example using vectors or maps? I can't seem to find an explicit answer to this question. I noticed that sets use maps, but then why not always use maps or always use sets. Instead 2 quite similar containers are provided. Thanks in advance.

Answer 1

Both std::set and std::map are associative containers. The difference is that std::sets contain only the key, while in std::map there is an associated value. Choosing one over the other depends mainly on what the task at hand is. If you want to build a dictionary of all the words that appear in a text, you could use a std::set<std::string>, but if you also want to count how many times each word appeared (i.e. associate a value to the key) then you would need an std::map<std::string,int>. If you don't need to associate that count, it does not make sense to have the int that is unnecessary.