C Programming Enumerations

Last modified by Microchip on 2023/11/09 09:06
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, ... , labeln}
Where compiler sets label0=0, label1=1, labeln=n

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

Example

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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,..., labeln}
Where compiler sets label0=const0, label1=(const0+1),...

Example

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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...,varNamen;

Example

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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...,varNamen;

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 the code.

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

Using Enumeration Type Variable

If enumeration and variable have already been defined:

varName = labeln;

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

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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)
{ ...