What does -> mean in C++?

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;