C++ introduces the reference operator,
&, which works slightly different than it does in C.
double a = 1; double b = &a; // b is now a pointer to a b = 2; // a now = 2
For those who come from a C background and understand pointers, treat it as though
double &b = a goes to
double *b = &a and all the subsequent usage of
b is replaced with
*b. Note that the double that
b points to cannot be changed! This is unlike a normal pointer,
double *b = &a, in where you could later write
b = &c. This will not work with a reference.
What Are They Good For?
References can simplify the syntax of certain pointer manipulation. They also useful when creating operator overloads, (e.g. the ++ operator for an enumeration), so that the syntax remains consistent with the base types in C++.