Enumerations

Enumerations are integer data types that you can create with a limited range of values. Each value is represented by a symbolic constant that may be used in conjunction with variables of the same enumerated type.

Enumerations:

Are unique integer data types
May only contain a specified list of values
Values are specified as symbolic constants

How to Create an Enumeration Type

Syntax

enum typeName {label₀, label₁,…, label_n}
Where compiler sets label₀=0, label₁=1, label_n=n

Creates an ordered list of constants. Each label’s value is one greater than the previous label.

Example

1	`enum` `weekday {SUN, MON, TUE, WED, THR, FRI, SAT};`

Label Values:
SUN = 0, MON = 1, TUE = 2, WED = 3, THR = 4 , FRI = 5, SAT = 6

Any label may be assigned a specific value. The following labels will increment from that value.

enum typeName {label₀ = const₀,…, label_n}
Where compiler sets label₀=const₀, label₁=(const₀+1),…

Example

1	`enum` `people {Rob, Steve, Paul = 7, Bill, Gary};`

Label Values:
Rob = 0, Steve = 1, Paul = 7, Bill = 8, Gary = 9

How to Declare an Enumeration Type Variable

Declared along with type:

Syntax

enum typeName {const-list} varname₁…;

Declared independently:

Syntax

enum typeName varName₁…,varName_n;

Example

enum weekday {SUN, MON, TUE, WED, THR, FRI, SAT} today;
 
enum weekday day;  //day is a variable of type weekday

Declaring a Tagless Enumeration Variable

No type name specified:

Syntax

enum {const-list} varName₁…,varName_n;

Only variables specified as part of the enum declaration may be of that type. No type name is available to declare additional variables of the enum type later in code.

1	`enum` `{SUN, MON, TUE, WED, THR, FRI, SAT} today;`

Using Enumeration Type Variable

If enumeration and variable have already been defined:

varName = label_n;

The labels may be used as any other symbolic constant. Variables defined as enumeration types must be used in conjunction with the type’s labels or equivalent integer.

Example

enum weekday {SUN, MON, TUE, WED, THR, FRI, SAT};
enum weekday day;
 
day = WED;
day = 6;               //May only use values from 0 to 6
if (day == WED)
{ …