What is main use of Enumeration?

Question

What is main use of Enumeration in c#?

Edited:- suppose I want to compare the string variable with the any enumeration item then how i can do this

Answer 1

An enumeration type (also named an enumeration or an enum) provides an efficient way to define a set of named integral constants that may be assigned to a variable.

http://msdn.microsoft.com/en-us/library/cc138362.aspx

Answer 2

Lets Take an Example we are taking normal constant in a class like int a=10;

by mistakely we assign new value to that variable in that same class like a=20; then we will get wrong data when we want access them. enum provide secure way of accessing constant.

Also if we have many feild constant in a class we had to memorize them if we want to use them in a class. but enum contains group of related name constant, if we want to access the constant then only we had to memorize enum name.

Answer 3

The definition in MSDN is a good place to start.

An enumeration type (also named an enumeration or an enum) provides an efficient way to define a set of named integral constants that may be assigned to a variable.

The main benefit of this is that constants can be referred to in a consistent, expressive and type safe way.

Take for example this very simple Employee class with a constructor:

You could do it like this:

public class Employee
{
    private string _sex;

    public Employee(string sex)
    {
       _sex = sex;
    }
}

But now you are relying upon users to enter just the right value for that string.

Using enums, you can instead have:

public enum Sex
{
    Male = 10,
    Female = 20
}

public class Employee
{
    private Sex _sex;

    public Employee(Sex sex)
    {
       _sex = sex;
    }
}    

This suddenly allows consumers of the Employee class to use it much more easily:

Employee employee = new Employee("Male");

Becomes:

Employee employee = new Employee(Sex.Male);

Answer 4

There are two meanings of enumeration in C#.

An enumeration (noun) is a set of named values. Example:

public enum Result {
  True,
  False,
  FileNotFound
}

Enumeration (noun form of the verb enumerate) is when you step through the items in a collection.

The IEnumerable<T> interface is used by classes that provide the ability to be enumerated. An array is a simple example of such a class. Another example is how LINQ uses it to return results as enumerable collections.

Edit:

If you want to compare a string to an enum value, you either have to parse the string to the enum type:

if ((Result)Enum.Parse(typeof(Result), theString) == Result.True) ...

or convert the enum value to a string:

if (theString == Result.True.ToString()) ...

(Be careful how you compare the values, depending on whether you want a case sensetive match or not.)

If you want to enumerate a collection and look for a string, you can use the foreach command:

foreach (string s in theCollection) {
  if (s == theString) {
    // found
  }
}