What does -> mean in C++? [duplicate]

It's to access a member function or member variable of an object through a pointer, as opposed to a regular variable or reference.

For example: with a regular variable or reference, you use the . operator to access member functions or member variables.

std::string s = "abc";
std::cout << s.length() << std::endl;

But if you're working with a pointer, you need to use the -> operator:

std::string* s = new std::string("abc");
std::cout << s->length() << std::endl;

It can also be overloaded to perform a specific function for a certain object type. Smart pointers like shared_ptr and unique_ptr, as well as STL container iterators, overload this operator to mimic native pointer semantics.

For example:

std::map<int, int>::iterator it = mymap.begin(), end = mymap.end();
for (; it != end; ++it)
    std::cout << it->first << std::endl;

a->b means (*a).b.

If a is a pointer, a->b is the member b of which a points to.

a can also be a pointer like object (like a vector<bool>'s stub) override the operators.

(if you don't know what a pointer is, you have another question)

1. Access operator applicable to (a) all pointer types, (b) all types which explicitely overload this operator

2. Introducer for the return type of a local lambda expression:

   std::vector<MyType> seq;
   // fill with instances...  
   std::sort(seq.begin(), seq.end(),
               [] (const MyType& a, const MyType& b) -> bool {
                   return a.Content < b.Content;
               });
   

3. introducing a trailing return type of a function in combination of the re-invented auto:

   struct MyType {
       // declares a member function returning std::string
       auto foo(int) -> std::string;
   };