It's basically a way to use the result of a pointer to a member. Let's say you have class Foo { int m_bar; int m_baz; } You want to store off w

It's basically a way to use the result of a pointer to a member. Let's say you have class Foo { int m_bar; int m_baz; } You want to store off which member of Foo you want to reference, but you want to do it in a way not tied to any specific instance of Foo. int (Foo :: * ptr) = &Foo::m_baz; // Basically offsetof() but safely typed. Cool, but now what are you going to do with that member? What if I want to set it to 10? int (Foo :: * ptr) = &Foo::m_baz; std::vector<Foo*> foos; ... // populate foos; for(Foo* foo : foos) { // For each foo, set whatever member ptr points at to 10 foo->*ptr = 10; } I've never seen it really used in practice (usually I see offsetof() and pointer math in this situation because the object type isn't known before hand) but it's an option.