Using auto or decltype for Function Pointer Types

If we know which function(s) we want to return, we can use decltype to simplify writing a function pointer return type. For example, assume we have two functions, both of which return a string::size_type and have two const string& parameters. We can write a third function that takes a string parameter and returns a pointer to one of these two functions as follows:

string::size_type sumLength(const string&, const string&);
string::size_type largerLength(const string&, const string&);

// depending on the value of its string parameter,
// getFcn returns a pointer to sumLength or to largerLength
decltype(sumLength) *getFcn(const string &);

The only tricky part in declaring getFcn is to remember that when we apply decltype to a function, it returns a function type, not a pointer to function type. We must add a * to indicate that we are returning a pointer, not a function.