The string class overloads many operators and
has numerous (over a hundred) member functions.
The length or size member function returns an unsigned integer value
that gives the number of characters currently in the string.
The string class actually defines a data type called size_type to store
the length or size of a string.
An example:
string firstname, fullname;
firstname = "George";
cout < < firstname.length( ) < < endl;
// prints 6
fullname = firstname + " Warren Bush";
cout < < fullname.size( ) < < endl;
// prints 18