What is the point of the 'auto' keyword?

Question

So I understand using var in C# makes sense because you have anonymous types that are compiler derived. C++ doesn\'t seem to have this feature (unless I\'m wron

Answer 1

C++ does have "anonymous" types - types you cannot refer to by name because the name is not available to you. This was the case even before C++11 and lambdas. Consider the following code:

class foo {
    class bar { 
      public:
        void baz() { }
    };
  public:        
    static bar func() { return bar(); }
};

foo::func().baz(); // OK, only the name "bar" is private
??? a = foo::func(); // Umm...
auto b = foo::func(); b.baz(); // Hooray!

Even if not actually declared in a private scope, it is often useful for a library to leave some types unspecified in its API - especially when heavily utilizing expression templates or other template metaprogramming where the type names can be arbitrarily long with all the nested template arguments. Even the standard itself does this - for instance, the result type of std::bind is not defined by the specification.