
## Table of Contents

1. [Introduction](#introduction)
2. [Define Enum with Power of Two](#define-enum-with-power-of-two)
3. [Define Enum with Bit Shift](#define-enum-with-bit-shift)
4. [Using the Enum Flags](#using-the-enum-flags)
5. [Conclusion](#conclusion)

## Introduction

A quick code snippet to show how to use enum flags by using the power of two. You
can define your enum and set the values as follows. This will make the
combined flag values unique.

## Define Enum with Power of Two

```
public enum MyType : uint {
		Undefined = 0,
		Type1 = 1,
		Type2 = 2,
		Type3 = 4,
		Type4 = 8,
		Type5 = 16
	}
```

## Define Enum with Bit Shift

Or you can use the bit shift if you don't want to count the numbers.

```
public enum MyType2 : uint {
		Undefined = 0,
		Type1 = 1,
		Type2 = 2 << 0,
		Type3 = 2 << 1,
		Type4 = 2 << 2,
		Type5 = 2 << 3
	}
```

## Using the Enum Flags

Following are a few ways to use this enum.

```
// set value
		var myvalue = MyType.Type1 | MyType.Type2;
		Console.WriteLine(myvalue);

		var myvalue2 = MyType2.Type1 | MyType2.Type2;
		Console.WriteLine(myvalue2);

		// check value
		if ((myvalue2 & MyType2.Type1) == MyType2.Type1) {
			Console.WriteLine("myvalue2 has Type1");
		}

		// check value
		if ((myvalue2 & MyType2.Type4) != MyType2.Type4) {
			Console.WriteLine("myvalue2 doesn't have type4");
		}
```

The above code result will be the following:

3
3
myvalue2 has Type1
myvalue2 doesn't have type4
myvalue2 has type4? False

## Conclusion

Using the `[Flags]` attribute and the power of two for enum values allows you to combine multiple enum values into a single variable and check for specific flags using bitwise operations.


A quick code snippet showing how to use C# enum flags with the power of two for defining combinable flag values.

How to Use C# Enum Flag


## Table of Contents

1. [Introduction](#introduction)
2. [Errors](#errors)
3. [Compilers](#compilers)
4. [Roslyn](#roslyn)
5. [NuGet Packages](#nuget-packages)
6. [WebConfig](#webconfig)
7. [Conclusion](#conclusion)
8. [References](#references)

## Introduction

You might have seen something like the following: your ASP.NET MVC solution builds fine but you get a compiler error when deploying to a local IIS site or a cloud web server. You know you have C# 6 or higher in your application, but you're not sure why it causes a compile error during runtime. I had to spend some time figuring out what was happening in my case, so I've documented what I found here to hopefully help someone else.

## Errors

```
Microsoft (R) Visual C# Compiler version 4.7.2556.0
for C# 5
Copyright (C) Microsoft Corporation. All rights reserved.

This compiler is provided as part of the Microsoft (R) .NET Framework, but only supports language versions up to C# 5, which is no longer the latest version. For compilers that support newer versions of the C# programming language, see http://go.microsoft.com/fwlink/?LinkID=533240

warning CS2008: No source files specified
error CS1541: Invalid reference option: 'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET
        Files\root\442dd867\' -- cannot reference directories
error CS1562: Outputs without source must have the /out option specified
```

## Compilers

It is confusing, but .NET development has several different .NET compilers. The compiler is `csc.exe`, but there are different versions:

  - .NET Framework's `csc.exe`

    - For example, .NET 4.6 is located here:
`C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe`

  - Visual Studio's `csc.exe`

    - Visual Studio 2013 is located here:
`C:\Program Files (x86)\MSBuild\12.0\Bin\csc.exe`

    - Visual Studio 2015 is located here:
`C:\Program Files (x86)\MSBuild\14.0\Bin\csc.exe`

  - Roslyn's `csc.exe` (example below uses version 1.0.0)

    - Roslyn inside application bin folder, for example:
`/bin/roslyn/csc.exe`

So there are multiple compilers in different locations, and unfortunately, the versions of `csc.exe` are different. If they were all the same version, I don't think I would see the error of compiling C# 6 code using a C# 5 compiler.

In summary, the following are the different versions when I checked:

  - .NET Framework's csc.exe - version 4.7.2556.0

  - Visual Studio 2013 - version 12.0.21005.1

  - Visual Studio 2015 - version 1.3.1.60616

  - Roslyn (1.0.0) - version 1.0.0.50618

```
C:\>"C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe"
Microsoft (R) Visual C# Compiler version 4.7.2556.0
for C# 5
Copyright (C) Microsoft Corporation. All rights reserved.

This compiler is provided as part of the Microsoft (R) .NET Framework, but only supports language versions up to C# 5, which is no longer the latest version. For compilers that support newer versions of the C# programming language, see http://go.microsoft.com/fwlink/?LinkID=533240

warning CS2008: No source files specified
error CS1562: Outputs without source must have the /out option specified

C:\>"C:\Program Files (x86)\MSBuild\12.0\Bin\csc.exe"
Microsoft (R) Visual C# Compiler version 12.0.21005.1
for C# 5
Copyright (C) Microsoft Corporation. All rights reserved.

warning CS2008: No source files specified
error CS1562: Outputs without source must have the /out option specified

C:\>"C:\Program Files (x86)\MSBuild\14.0\Bin\csc.exe"
Microsoft (R) Visual C# Compiler version 1.3.1.60616
Copyright (C) Microsoft Corporation. All rights reserved.

warning CS2008: No source files specified.
error CS1562: Outputs without source must have the /out option specified

C:\>"C:\projects\WebApplication1\WebApplication1\bin\roslyn\csc.exe"
Microsoft (R) Visual C# Compiler version 1.0.0.50618
Copyright (C) Microsoft Corporation. All rights reserved.

warning CS2008: No source files specified.
error CS1562: Outputs without source must have the /out option specified
```

That's why when I build the solution with Visual Studio 2015, it works fine because it uses a different `csc.exe`, but errors sometimes appear when deploying to local IIS or the cloud. Also, ASP.NET MVC Razor uses a different compiler than C#. For example, if you have the following code, with a target framework of 4.6 and you're not using Roslyn, it will build fine but you'll see a compiler error when deploying locally.

```
@model WebApplication1.Models.MyModel
@if (string.IsNullOrWhiteSpace(Model.Test?.ToLower()))
{

}
```

## Roslyn

It looks like things are moving toward using `Roslyn`, so make sure these two NuGet packages are available in your solution: `Microsoft.CodeDom.Providers.DotNetCompilerPlatform` and `Microsoft.Net.Compilers`. Also, make sure the web.config changes are applied. Roslyn should be able to determine what version is appropriate for your solution.

It should be simple — just add the following NuGet packages. But make sure the web.config is updated. Sometimes I've had the issue where the web.config is updated locally but the IIS site's web.config is not updated, so it ends up not using Roslyn and instead using the .NET Framework's `csc.exe` compiler.

### NuGet Packages

1. Microsoft.CodeDom.Providers.DotNetCompilerPlatform

2. Microsoft.Net.Compilers

### WebConfig

```






```

## Conclusion

When deploying ASP.NET MVC applications that use C# 6 or later features, you may encounter compiler errors because the default .NET Framework `csc.exe` only supports up to C# 5. The solution is to install the Roslyn NuGet packages (`Microsoft.CodeDom.Providers.DotNetCompilerPlatform` and `Microsoft.Net.Compilers`) and ensure the web.config is properly updated to use Roslyn as the compiler.

## References

  - Command-line build with csc.exe

  - How to add dynamic compilation to your C# projects?

  - Github - roslyn

  - Removing roslyn from ASP.NET 4.5.2 project template

  - Publish website without roslyn


.NET Compiler Roslyn


## Table of Contents

1. [Introduction](#introduction)
2. [RSS Feeds](#rss-feeds)
3. [Forums](#forums)
4. [Other Resources](#other-resources)
5. [Conclusion](#conclusion)

## Introduction

The following are a few resources you can use to learn .NET.

## RSS Feeds

1. http://www.asp.net

2. https://blogs.msdn.microsoft.com

3. http://sxp.microsoft.com

4. https://channel9.msdn.com

## Forums

- http://forums.dotnetfoundation.org

## Other Resources

- channel9.msdn.com

- gitter.im

- dotnet.github.io

- blogs.msdn.microsoft.com

## Conclusion

These resources provide a solid starting point for learning .NET. From official Microsoft blogs and RSS feeds to community forums, you'll find plenty of material to deepen your understanding of the .NET ecosystem.


A curated list of resources to learn .NET, including RSS feeds, forums, and other useful links.

.NET

How to Use C# Enum Flag

.NET Compiler Roslyn

List of Resources to Learn .NET