C++ Primer, Fifth Edition

12.1.1. The shared_ptr Class

Like vectors, smart pointers are templates (§ 3.3, p. 96). Therefore, when we create a smart pointer, we must supply additional information—in this case, the type to which the pointer can point. As with vector, we supply that type inside angle brackets that follow the name of the kind of smart pointer we are defining:

shared_ptr<string> p1;    // shared_ptr that can point at a stringshared_ptr<list<int>> p2; // shared_ptr that can point at a list of ints

A default initialized smart pointer holds a null pointer (§ 2.3.2, p. 53). In § 12.1.3 (p. 464), we’ll cover additional ways to initialize a smart pointer.

We use ...