Definitions

Aliasing is the practice of referring to one object by more than one “name”; in C++ these names are actually pointers or references.

The aliasing problem is a name for the difficulties caused by altering a shared object.

An enum is a way to define a number of unchangeable values, which are quite similar to consts. The value of each successive name in an enum is automatically incremented from the value of the previous name (if you don't specify another value explicitly). The term enum is short for “enumeration”, which is a list of items.

The switch statement is functionally equivalent to a number of if/else statements in a row, but is easier to read and modify. The keyword switch is followed by a selection expression (in parentheses), which specifies an expression used to select an alternative section of code. The various alternatives to be considered are enclosed in a set of curly braces following the selection expression and are marked off by the keyword case followed by the (constant) value to be matched and a colon.

An array initialization list is a list of values that are used to initialize the elements of an array. The ability to specify a list of values for an array is built into the C++ language and is not available for user-defined data types such as the Vec.