13th Zhang Yi type and bit mark [". NET Framework Program design" Reading notes]

. NET Framework | notes | procedure | Design 13th Zhang Yi type and bit mark

One, enum type

1, the use of enumerated types of reasons:

L enumeration type is to make the program easier to write, read, maintain, in the code in the use of symbolic names to replace the number is a consistent idea of programming.

L strongly typed, easy to type test

2, Attention matters:

L Enum type inherits from System.enum,system.enum and inherits from System.valurtype

L Enumeration types cannot define methods, properties, events

L enumeration types are constants rather than read-only fields, so it is possible to introduce version problems (see chapter eighth for a discussion)

L Define the enumeration type on the same level as the type that references it, reducing the amount of code entry



3, System.Enum in the application of the method:

L public static type Getunderlyingtype (type enumtype);
Gets the underlying type for saving an instance of an enumerated type. The underlying type syntax used to declare an enumeration type is as follows:
Enum Human:byte
{
Male,
Female
}
The above method is invoked Enum.getunderlyingtype (typeof (Human)) and will be returned to System.Byte;
L public override string ToString ();
public string ToString (string); parameter is a format string
public static string format (Type enumtype,object value,string format);
value– the value to convert, format– format string (g,g,x,x,d,d,f,f)
L public static Array GetValues (Type enumtype);
Gets an array of constant values in the enumeration
L public static string GetName (Type enumtype,object value);
Retrieves the name of a constant with the specified value in the specified enumeration
L public static string[] GetNames (Type enumtype);
Retrieves an array of constant names in the specified enumeration.
L public static Object Parse (Type, String);
public static Object Parse (Type, string, bool);
Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumeration object
L public static bool IsDefined (Type enumtype,object value);
Returns the indication of whether a constant with the specified value exists in the specified enumeration, value or name of the constant
L Series Toobject method
Returns an instance of the specified enumeration type set to the specified value
Second, bit mark

L Use the System.flagsattributes customization feature so that the ToString or Format method can look for each matching symbol in an enumerated value, concatenate them into a string, and separate them with commas; The parse method can split a string and get a composite enumeration type by using the attribute

l use the format string F or F to have the same effect

The following example illustrates the above situation

Using System;



[Flags]//Custom Features

public enum Human:byte//custom base type

{

Male = 0x01,

Female = 0x10

}



public class Enumtest

{

public static void Main ()

{

Human Human = Human.male | Human.female; Hybrid?



Console.WriteLine (Human. ToString ()); Conditions for customizing attributes using Flags

Console.WriteLine (Human. ToString ("F")); No custom features are used with flags



Console.WriteLine (Enum.format (typeof (Human), Human, "G"))//Use flags to customize features

Console.WriteLine (Enum.format (typeof (Human), Human, "F"))//No use of flags custom features



Human = (human) Enum.parse (typeof (Human), "17");

Console.WriteLine (Human. ToString ()); Conditions for customizing attributes using Flags

Console.WriteLine (Human. ToString ("F")); No custom features are used with flags

}

}



/* Run Results

Male, Female

Male, Female

Male, Female

*/

Note: The annotations in the above program are syntax when the flags feature is not used