"You must know. NET"-Simplicity: Understanding Enumerations (Ⅲ)

The main contents of this section include:

Enumeration type full solution;

bit marking applications;

Enumerates the application rules.

Ⅰ, enumerating

　　Where can I see the enumeration? Open the properties of each file, we will see a read-only, hidden options, when you manipulate a file, you can use a read-only, writable, append and other modes.

In. NET you can choose to express this simple classification structure in static fields of the class, but the wiser choice is obviously--enumeration!

All enum types are implicitly and implicitly inherited from the System.Enum type, the System.Enum type is a reference type, and the only reference type that inherits from System.ValueType is not a value type.

An enumeration type is a value type that is assigned to the thread's stack and automatically inherits from the enum type, but cannot be inherited by itself; The enum type is a reference type and is assigned to the managed heap, and the enum itself is not an enumeration type, but it provides a common method for manipulating enumeration types.

        Public enum Week:int        {            Sun = 7,            Mon = 1,            Tue, Wed, Thur, Fri, Sat,            weekend = Sun        }
A. Type conversions: Because enum types are essentially collections of certificate types, you can type conversions with integer types to each other, but must be explicit.

            int i = (int) Week.fri;            Week J = (week) 3;

Or use the Parse method to do it indirectly. Week W = (week) Enum.parse (typeof (Week), "2");

B. Mapping to a string:

Includes the ToString instance method and the parse static method.

C. Reciprocal conversions of different enumerations: display transformations, such as

Otherweek i = Otherweek.mon;

Week today = (week) I;

D. Other reference type conversions:

Enum inherits from--valuetype,icomparable,iformattable,iconvertible.

Therefore, you can explicitly convert the above types, and System.Object, System.Enum.

E. Common methods:

GetNames, gets an array of symbol names in the enumeration;

GetValues, gets all the symbol arrays in the enumeration;

IsDefined, determines whether the symbol or integer exists in the enumeration;

A getunderlyingtype that returns the declaration type of the enumeration instance.
　　　　

Ⅱ, Bit enumeration

　　An enumeration marked with the [Flags] attribute. The purpose of the FlagsAttribute attribute is to treat an enumeration member as a bit token, rather than as an orphaned constant.　　

The a.enum.isdefined method cannot handle a bit enumeration member, which can be used with the enumeration member for a bitwise AND operation, and a result of not 0 indicates that the variable contains the enumeration member, as
if ((Test & color.red)!=0)  
The B.flags feature affects the execution process and results of the ToString, parse, and format methods.

　　

　　

"You must know. NET"-Simplicity: Understanding Enumerations (Ⅲ)