Type Compatibility between Enums in Visual C#

Making QR in Visual C# Type Compatibility between Enums
Type Compatibility between Enums
QR Code JIS X 0510 Drawer In C#.NET
Using Barcode generation for .NET framework Control to generate, create QR Code ISO/IEC18004 image in Visual Studio .NET applications.
6 discussed that C# does not support covariance (type compatibility) between arrays of derived types For example, Contact[] will not cast to PdaItem[] C# also does not support a direct cast between arrays of two different enums However, there is a way to coerce the conversion by casting first to an array and then to the second enum The requirement is that both enums share the same underlying type, and the trick is to cast first to SystemArray, as shown at the end of Listing 812
Barcode Printer In Visual C#.NET
Using Barcode printer for .NET Control to generate, create bar code image in VS .NET applications.
Listing 812 Casting between Arrays of Enums
QR Code ISO/IEC18004 Creation In .NET
Using Barcode encoder for ASP.NET Control to generate, create QR Code ISO/IEC18004 image in ASP.NET applications.
enum ConnectionState1 { Disconnected, Connecting, Connected, Disconnecting } ___________________________________________________________________________ ___________________________________________________________________________ enum ConnectionState2 { Disconnected, Connecting, Connected, Disconnecting } ___________________________________________________________________________ ___________________________________________________________________________ class Program {
Generate QR Code In VS .NET
Using Barcode encoder for .NET framework Control to generate, create QR Code image in .NET framework applications.
static void Main() { ConnectionState1[] states = (ConnectionState2[]) (Array) new ConnectionState2[42]; } }
Painting QR In Visual Basic .NET
Using Barcode creator for .NET framework Control to generate, create QR-Code image in .NET framework applications.
Converting between Enums and Strings
Paint Bar Code In C#.NET
Using Barcode maker for VS .NET Control to generate, create bar code image in VS .NET applications.
One of the conveniences associated with enums is the fact that the ToString() method, which is called by methods like SystemConsoleWriteLine(), writes out the enum value identifier: SystemDiagnosticsTraceWriteLine(stringFormat( "The Connection is currently {0}", ConnectionStateDisconnecting));
Barcode Generator In C#
Using Barcode generator for .NET framework Control to generate, create barcode image in Visual Studio .NET applications.
The preceding code will write the text in Output 83 to the trace buffer
Code 39 Extended Drawer In C#
Using Barcode creator for Visual Studio .NET Control to generate, create Code 3 of 9 image in Visual Studio .NET applications.
Output 83
Code128 Creation In C#.NET
Using Barcode creation for .NET framework Control to generate, create Code 128A image in .NET applications.
The Connection is currently Disconnecting
Printing Data Matrix ECC200 In C#
Using Barcode encoder for .NET Control to generate, create ECC200 image in Visual Studio .NET applications.
Conversion from a string to an enum is a little harder to find because it involves a static method on the SystemEnum base class or, via inheritance, on the enum type Listing 813 provides an example of how to do it, and Output 84 shows the results
DataMatrix Printer In Visual Studio .NET
Using Barcode printer for .NET Control to generate, create Data Matrix 2d barcode image in .NET framework applications.
Listing 813 Converting a String to an Enum
UPC-A Encoder In .NET
Using Barcode generator for ASP.NET Control to generate, create UPC A image in ASP.NET applications.
ThreadPriorityLevel priority = (ThreadPriorityLevel)EnumParse( typeof(ThreadPriorityLevel), "Idle"); ConsoleWriteLine(priority);
Painting ANSI/AIM Code 39 In VB.NET
Using Barcode creator for .NET Control to generate, create ANSI/AIM Code 39 image in .NET applications.
Output 84
Barcode Recognizer In VS .NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET applications.
Idle
Paint GTIN - 128 In Java
Using Barcode creation for Java Control to generate, create EAN128 image in Java applications.
The first parameter to EnumParse() is the type, which you specify using the keyword typeof() This is a compile-time way of identifying the type, like a literal for the type value (see 14) Unfortunately, there is no tryParse() method, so code should include appropriate exception handling if there is a chance the string will not correspond to an enum value identifier The key caution about casting from a string to an enum, however, is that such a cast is not localizable Therefore, developers should use this type of cast only for messages that are not exposed to users (assuming localization is a requirement)
Decode Code 128 Code Set A In VS .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Enums as Flags
Making Bar Code In Visual Basic .NET
Using Barcode printer for VS .NET Control to generate, create barcode image in Visual Studio .NET applications.
Many times, developers not only want enum values to be unique, but they also want to be able to combine them to represent a combinatorial value For example, consider SystemIOFileAttributes This enum, shown in Listing 814, indicates various attributes on a file: read-only, hidden, archive, and so on The difference is that unlike the ConnectionState attribute, where each enum value was mutually exclusive, the FileAttributes enum values can and are intended for combination: A file can be both read-only and hidden To support this, each enum value is a unique bit (or a value that represents a particular combination)
ECC200 Drawer In Java
Using Barcode generation for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
Listing 814 Using Enums As Flags
Painting Code 128 Code Set C In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create USS Code 128 image in .NET applications.
public enum FileAttributes { ReadOnly = 2^0, Hidden = 2^1, System = 2^2, Directory = 2^4, Archive = 2^5, Device = 2^6, Normal = 2^7, Temporary = 2^8, SparseFile = 2^9, ReparsePoint = 2^10, Compressed = 2^11, Offline = 2^12, NotContentIndexed = 2^13, Encrypted = 2^14, }
DataMatrix Creation In Visual Basic .NET
Using Barcode printer for Visual Studio .NET Control to generate, create ECC200 image in .NET framework applications.
// // // // // // // // // // // // // //
000000000000001 000000000000010 000000000000100 000000000010000 000000000100000 000000001000000 000000010000000 000000100000000 000001000000000 000010000000000 000100000000000 001000000000000 010000000000000 100000000000000
Because enums support combined values, the guideline for the enum name of bit flags is plural To join enum values you use a bitwise OR operator, as shown in Listing 815
Listing 815 Using Bitwise OR and AND with Flag Enums
using System; using SystemIO; public class Program { public static void Main() { // string fileName = @"enumtesttxt"; SystemIOFileInfo file = new SystemIOFileInfo(fileName); fileAttributes = FileAttributesHidden | FileAttributesReadOnly; ConsoleWriteLine("{0} | {1} = {2}", FileAttributesHidden, FileAttributesReadOnly, (int)fileAttributes); if ( (fileAttributes & FileAttributesHidden) !=
FileAttributesHidden) { throw new Exception("File is not hidden"); } if (( fileAttributes & FileAttributesReadOnly) != FileAttributesReadOnly) { throw new Exception("File is not read-only"); } // }
The results of Listing 815 appear in Output 85
Output 85
Hidden | ReadOnly = 3
Using the bitwise OR operator allows you to set the file to both read-only and hidden In addition, you can check for specific settings using the bitwise AND operator Each value within the enum does not need to correspond to only one flag It is perfectly reasonable to define additional flags that correspond to frequent combinations of values Listing 816 shows an example