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C# Beyond Basics

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Enumerators

Enum, also known as Enumerator, is a structure for grouping together some integral constants. The constants are basically of the type int.

Following is the syntax for creating an enum:

cs

index

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enum EnumName
{
Const1,
Const2,
Const3,
...
}

              
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enum EnumName 
{
    Const1,
    Const2,
    Const3,
    ...
}

By default the first element of an enum has the value 0, the second element has a value 1 and so on.

For-example:

cs

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

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

We can access the values of these constants using the enumName.constantName syntax.

For-example:

cs

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using System;

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

class ConsoleApp
{
static void Main(string[] args)
{
// Explicitly converting the enum elements to 'int' and then outputting them
Console.WriteLine((int)Days.Monday); // 0
Console.WriteLine((int)Days.Wednesday); // 2
Console.WriteLine((int)Days.Friday); // 4
Console.WriteLine((int)Days.Sunday); // 6
}
}

              
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using System;

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

class ConsoleApp
{
    static void Main(string[] args)
    {
        // Explicitly converting the enum elements to 'int' and then outputting them
        Console.WriteLine((int)Days.Monday);        // 0
        Console.WriteLine((int)Days.Wednesday);     // 2
        Console.WriteLine((int)Days.Friday);            // 4
        Console.WriteLine((int)Days.Sunday);            // 6
    }
}

Note that in the above example we explicitly need to convert the constant into an int datatype since these constants are of type Days by default, which means that the enum Days is a new datatype which we created. Therefore, it can be stored into a variable of type Days:

python
Days day = Days.Friday;

This is useful in places like switch statements.

For-example:

cs

index

copy
using System;

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

class ConsoleApp
{
static void Main(string[] args)
{
Days day = Days.Friday;

switch (day)
{
case Days.Monday:
Console.WriteLine("It is Monday");
break;
case Days.Tuesday:
Console.WriteLine("It is Tuesday");
break;
case Days.Wednesday:
Console.WriteLine("It is Wednesday");
break;
case Days.Thursday:
Console.WriteLine("It is Thursday");
break;
case Days.Friday:
Console.WriteLine("It is Friday");
break;

              
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748

            
using System;

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

class ConsoleApp
{
    static void Main(string[] args)
    {
        Days day = Days.Friday;

        switch (day)
        {
            case Days.Monday:
                Console.WriteLine("It is Monday");
                break;
            case Days.Tuesday:
                Console.WriteLine("It is Tuesday");
                break;
            case Days.Wednesday:
                Console.WriteLine("It is Wednesday");
                break;
            case Days.Thursday:
                Console.WriteLine("It is Thursday");
                break;
            case Days.Friday:
                Console.WriteLine("It is Friday");
                break;
            case Days.Saturday:
                Console.WriteLine("It is Saturday");
                break;
            case Days.Sunday:
                Console.WriteLine("It is Sunday");
                break;
            default:
                Console.WriteLine("Invalid Day");
                break;
        }
    }
}

We can also manually assign values to the enum constants. The unassigned constants take up incremented values of the previous elements:

cs

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using System;

enum Days
{
Monday,
Tuesday,
Wednesday = 5,
Thursday,
Friday,
Saturday = 10,
Sunday
}

class ConsoleApp
{
static void Main(string[] args)
{
// Explicitly converting the enum elements to 'int' and then outputting them
Console.WriteLine((int)Days.Monday);
Console.WriteLine((int)Days.Tuesday);
Console.WriteLine((int)Days.Wednesday);
Console.WriteLine((int)Days.Thursday);
Console.WriteLine((int)Days.Friday);
Console.WriteLine((int)Days.Saturday);
Console.WriteLine((int)Days.Sunday);
}
}

              
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using System;

enum Days
{
    Monday,
    Tuesday,
    Wednesday = 5,
    Thursday,
    Friday,
    Saturday = 10,
    Sunday
}

class ConsoleApp
{
    static void Main(string[] args)
    {
        // Explicitly converting the enum elements to 'int' and then outputting them
        Console.WriteLine((int)Days.Monday);
        Console.WriteLine((int)Days.Tuesday);
        Console.WriteLine((int)Days.Wednesday);
        Console.WriteLine((int)Days.Thursday);
        Console.WriteLine((int)Days.Friday);
        Console.WriteLine((int)Days.Saturday);
        Console.WriteLine((int)Days.Sunday);
    }
}

1. What is an enum in C#?

2. Which keyword is used for defining an enum?

3. In an enum, what is the default underlying type for the values?

question mark

What is an enum in C#?

Select the correct answer

question mark

Which keyword is used for defining an enum?

Select the correct answer

question mark

In an enum, what is the default underlying type for the values?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 2. Chapter 10

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