Enums as Array Indexes

Chapter 8

Integral Data Type and Array Indices

C++ allows any integral type to be used as an array index. Therefore, we can use defined enumeration types to improve readability.

Example:

enum Color {GREEN, RED, BLUE, BROWN, WHITE, ORANGE, YELLOW, NO_COLOR};

double paintPrice[NO_COLOR]; // Array of 7 doubles (NO_COLOR == 7)

// initialize the prices to $1
for (Color paint = GREEN; paint < NO_COLOR;
    paint = static_cast<Color>(paint + 1))
{
    paintPrice[paint] = 1.0;
}
paintPrice[RED] = paintPrice[RED] + 75.96;

Declare Arrays Using Type Aliases

You may use type aliasing to have a new name for an array of a particular type and size.

Example:

// Use a constant for the size and declare an alias “typedef”
const int SIZE = 50;
using list = double[SIZE];

list yourList; // an array of 50 doubles called yourList
list myList; // another array of 50 doubles called myList