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C# Object-Oriented (OOP)

C# Enumeration (Enum)

In C#, enum (enumeration type) is used to assign constant names to a set of integer values. It makes constant values more readable, for example, WeekDays.Monday is more readable when referring to a day of the week than the number 0.

Enumerations are defined directly using the enum keyword within a namespace, class, or structure. All constant names can be declared within the braces and separated by commas. Below is defined the enumeration for weekdays.

Example: Define an Enumeration

enum WeekDays
{
　　　　Monday
　　　　Tuesday
　　　　Wednesday
　　　　Thursday,
　　　　Friday,
　　　　Saturday,
　　　　Sunday
}

Above, the WeekDays enumeration declares members on each line, separated by commas.

Enumeration Values

If no value is assigned to an enumeration member, the compiler will assign integer values (starting from zero) by default to each member. The first member of the enumeration will be 0, and the value of each subsequent enumeration member will increase1.

Example: Default Enumeration Value

enum WeekDays
{
　　　　Monday　　　　　//　0
　　　　Tuesday　　　　//　1
　　　　Wednesday　　//　2
　　　　Thursday,　　　//　3
　　　　Friday,　　　　　//　4
　　　　Saturday,　　　//　5
　　　　Sunday　　　　　　//　6
}

You can assign different values to enumeration members. Changing the default value of enumeration members will automatically assign incremental values in order to other members.

Example: Assigning Values to Enumeration Members

enum Categories
{
　　　　Electronics,　　　　//　0
　　　　Food,　　　　　　　　　　　//　1
　　　　Automotive =　6,　//　6
　　　　Arts,　　　　　　　　　　　//　7
　　　　BeautyCare,　　　　　//　8
　　　　Fashion　　　　　　　　　//　9
}

You can even assign different values to each member.

Example: Assigning Values to Enumeration Members

enum Categories
{
　　　　Electronics =　1,　　
　　　　Food =　5,　
　　　　Automotive =　6,　
　　　　Arts =　10,　
　　　　BeautyCare =　11,　
　　　　Fashion =　15,
　　　　WomanFashion =　15
}

Enumerations can be of any numeric data type, such as byte, sbyte, short, ushort, int, uint, long, or ulong. However, enumerations cannot be of string type.

Specify the type after the enum name as :type. Below is defined a byte enum.

Example: Byte Enumeration

enum Categories: byte
{
　　　　Electronics =　1,　　
　　　　Food =　5,　
　　　　Automotive =　6,　
　　　　Arts =　10,　
　　　　BeautyCare =　11,　
　　　　Fashion =　15
}

Access an enumeration

You can use dot notation: enum.member to access enumeration

Example: Accessing Enumeration

enum WeekDays
{
　　　　Monday　
　　　　Tuesday
　　　　Wednesday
　　　　Thursday,　
　　　　Friday,　
　　　　Saturday,
　　　　Sunday　
}
Console.WriteLine(WeekDays.Monday);　//　Monday
Console.WriteLine(WeekDays.Tuesday);　//　Tuesday
Console.WriteLine(WeekDays.Wednesday);　//　Wednesday
Console.WriteLine(WeekDays.Thursday);　//　Thursday
Console.WriteLine(WeekDays.Friday);　//　Friday
Console.WriteLine(WeekDays.Saturday);　//　Saturday
Console.WriteLine(WeekDays.Sunday);　//　Sunday

Convert Enumeration

Explicit casting is required to convert from enumeration type to its base integer type.

Example: Enumeration Conversion

enum WeekDays
{
　　　　Monday　
　　　　Tuesday
　　　　Wednesday
　　　　Thursday,　
　　　　Friday,　
　　　　Saturday,
　　　　Sunday　
}
Console.WriteLine(WeekDays.Friday);　//Output: Friday　
int day = (int) WeekDays.Friday;　//　Conversion from enum to int
Console.WriteLine(day);　//Output:4　
var wd = (WeekDays)　5;　//　Conversion from int to enum
Console.WriteLine(wd);//Output: Saturday

enum is an abstract class.

C# FileInfo C# Structure (Struct)