enum in C# and conversion

An enumeration type (also known an enumeration or an enum) provides an efficient way to define a set of named integral constants that may be assigned to a variable to make programming clear, understandable and manageable. There are ways of using, like how to use enum in switch and case statement, how to convert a text to enum or number to enum to compare, we will discuss here all these points in detail.

Let’s first understand the basics of enum in C#

• The body of an enum type declaration defines zero or more enum members, which are the named constants of the enum type.
• No two enum members can have the same name.

• Each enum member has an associated constant value.

• By default the underlying type of each element in the enum is int.

• All the underlying elements by default are public
• You can verify the underlying numeric values by casting to the underlying type (we will see it in this article latter).

How to create enum

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

In this case all the underlying elements type is integer so how to change elements type to something different than integer, can we do this, yes, to do this we can provide other integral type after colon like we inherit a class from other class, see this

public enum Months : byte 
{ 
  Jan, Feb, Mar,  Apr, May, Jun,  Jul, Aug, Sep,  Oct, Nov, Dec 
}

In this case all the underlying elements type is byte. In both the above case we have not defined any integer value to any element but it will contain from 1 to n, it doesn’t start from 0 as in the case of array but from 1. I there any way to define an enum with my own values, yes, let’s see this, suppose we want to create an enum category which start from 100 and 200 and so on then

public enum CarCategory
{
Convertible = 100,
Hatchback = 200,
Sedan = 300,
SUV = 400,
VAN = 500,
Truck = 600,
Wagon = 1000
}

As you can see here we used 1000 for Wagon after Truck =600, so sequential increment is not needed, other thing we need to note here is value assigned to any member can not exceed the range of underlying type, let's see this

enum xyz : uint
{
  x   =-1,
  y = -2,
  z = -3
}

It is wrong because -1, -2, -3 etc. out of range of uint.

Have you ever tried to use enum in switch case statement, let's see how we can do this, we will use CarCategory for this example, suppose we are getting integer value from our code and we have to use that integer in switch and execute matching category then

Int32[]arr = {100, 300, 1000};
foreach (Int32 category in arr)
{
   switch ((CarCategory)category)
   {
        case CarCategory.Convertible:
           // Do something
           break;
        case CarCategory.Hatchback:
           // Do something
           break;
        .........................
        .........................            
        default: break;
   }
}

We convert our integer value to CarCategory enum in siwtch, if any item match it will execute matching case if not then execute default case. Suppose we are getting a value 2000 which is not defined in our enum, what will happen then, will it give error, no it will execute default case, let try to convert some number into car category enum

(CarCategory)100 => Convertible 
(CarCategory)500 => VAN
(CarCategory)1000 => Wagon 
(CarCategory)2000 =>  2000 and type would be CarCategory

How to get enum member's integer and string value?

CarCategory.Wagon.ToString(); 
// result : Wagon 
Convert.ToInt32(CarCategory.Wagon);
// result : 1000
// same we can use like this
(String)CarCategory.Wagon;
(int)CarCategory.Wagon;

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