What is an ENUM
Enum is the short for enumeration. it can be use-full to make your code more readable.
For example :
We have a Class Named Person.cs and this class has a property "Status".
without use of Enums
Person.status = 3;
It doesnt tell us what the status stands for.
with use of Enums
using System;
public enum MyEnumeration
{
Single = 1,
Married= 2,
Widow = 3
}
Person.status = MyEnumeration.Widow;
Another Advantage of using enums is the following situation.
We Forgot to add the Devorced Status.
We change our Enum :
public enum MyEnumeration
{
Single = 1,
Married= 2,
Devorced = 3,
Widow = 4
}
if we coded without enum, the status of the person is changed from Widow to Devorced.
With use of enum, the status is still Widow after adding the devorced state
SIMPLE ENUM OPERATIONS
string Mystring = "Single";
int intval = 3;
//string to enum
//----------------------------------------------
//without extention methodMyEnumeration myitem = (MyEnumeration)Enum .Parse(typeof( MyEnumeration), Mystring);
//with extention method
MyEnumeration item = Mystring.ParseToEnum<MyEnumeration >();
//int to enum
//----------------------------------------------
//without extention method
MyEnumeration item = (MyEnumeration )intval;
//with extention method
MyEnumeration item2 = intval.ParseToEnum<MyEnumeration >();
//enum to string
//----------------------------------------------
//without extention method
string name1 = Enum .GetName(typeof( MyEnumeration), MyEnumeration.Married);
//with extention method
string name = MyEnumeration .Married.GetName();
//enum to int
//----------------------------------------------
//without extention method
int val = (int )MyEnumeration.Married;
//with extention method
int val1 = MyEnumeration .Married.GetValue();
Loop Trough enum
foreach ( string value in Enum.GetNames( typeof(MyEnumeration)))
{
valueList.ValueListItems.Add(value);
}
Extention methods to work with enums
public static int GetValue( this Enum EnumValue)
{
return (int )(Enum.ToObject(EnumValue.GetType(),EnumValue));
}
public static string GetName( this Enum EnumValue)
{
return (Enum .GetName(EnumValue.GetType(),EnumValue));
}
public static T ParseToEnum( this string value)
{
Type TypeOfDestObj = typeof (T);
if (!TypeOfDestObj.IsEnum) throw new ArgumentException("is no enum" );
return (T)Enum .Parse(TypeOfDestObj, value);
}
public static T ParseToEnum( this int value)
{
Type TypeOfDestObj = typeof (T);
if (!TypeOfDestObj.IsEnum) throw new ArgumentException("is no enum" );
return (T)Convert .ChangeType(value, TypeOfDestObj);
}
Extention methods to loop trough enums
public static Dictionary< int , string > ToDictionaryWithValueAsKey( this object obj)
{
Dictionary <int , string> rets = new Dictionary < int, string >();
Type MyType = obj.GetType();
if (!MyType.IsEnum) throw new ArgumentException ("is not an enum" );
var vals = Enum .GetValues(MyType);
var names = Enum .GetNames(MyType);
for (int i = 0; i < names.Length; i++)
{
int val = (int )vals.GetValue(i);
string name = names.GetValue(i) as string;
rets.Add(val, name);
}
return rets;
}
public static Dictionary< string , int > ToDictionaryWithNameAsKey( this object obj)
{
Dictionary <string , int> rets = new Dictionary < string, int >();
Type MyType = obj.GetType();
if (!MyType.IsEnum) throw new ArgumentException ("is not an enum" );
var vals = Enum .GetValues(MyType);
var names = Enum .GetNames(MyType);
for (int i = 0; i < names.Length; i++)
{
int val = (int )vals.GetValue(i);
string name = names.GetValue(i) as string;
rets.Add(name,val);
}
return rets;
}
What to do if you need String Values instead of int values
You can also use other types than int.
But what to do with strings?
1. Create a Custom attribute
public class StringValueAttribute : System.Attribute
{
private string _value;
public StringValueAttribute(string value)
{
_value = value;
}
public string Value
{
get { return _value; }
}
}
2. Add the custom attribute to the enum
public enum MyEnumeration
{
[ StringValueAttribute("Y" )]
Young = 1,
[ StringValueAttribute("M" )]
Middelaged = 2,
[ StringValueAttribute("O" )]
Old = 3
}
2. Create an ExtentionMethod to get te stringvalue
public static string GetStringValue( this Enum value)
{
return (from members in value.GetType().GetMember(value.ToString())
let atts= (StringValueAttribute)members.GetCustomAttributes(typeof (StringValueAttribute), false).FirstOrDefault()
select attributes == null ? value.ToString() : attributes.Value).FirstOrDefault();
}
3. Use it
int intval = 3;
MyEnumeration item3 = intval.ParseToEnum<MyEnumeration >();
string stringval = item3.GetStringValue();
