How to have a set of structs in C++

Question

I have a struct which has a unique key. I want to insert instances of these structs into a set. I know that to do this the < operator has to be overloaded so that set can mak

Answer 1

see ereOn's answer, it's right.

The real problem in you code is this:

foo *test = new foo;
test->key = 0;
bar.insert(test);

You insert a pointer in the set, not a struct. Change the insert to:

 bar.insert( *test );
 //          ^

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EDIT: but then you'll need to delete foo, as it will be copied in the set. Or just create it on the stack (using set with pointers is not a good idea, because the arrangement will be "strange" - the set will sort according to the pointers' addresses )