Feature 'interpolated strings' is not available in C# 5. Please use language version 6 or greater.

Question

The following line does not compile when I put in a Razor View.

var extPropLookupNameCompania = $\"extension_{SettingsHelper.ClientId.Replace(\"-\", \"\")}_{         


        

Answer 1

The key is to see the compilerOptions="/langversion:6 portion of the following in your web.config. Without it I got errors trying to use string interpolation inside a .cshtml file.

  <system.codedom>
    <compilers>
      <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701" />
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+" />
    </compilers>
  </system.codedom>

Answer 2

If you are experiencing this error in a .NET Framework 4.5.1 project, upgrading to 4.5.2 solves the problem.

Answer 3

You have to encapsulate it with braces like this:

EDIT: I updated because there was a missing curly.

var extPropLookupNameCompania = $("{extension_{SettingsHelper.ClientId.Replace("-", "")}_{"Compania"}");

I tried the following successfully:

 @($"It is {DateTime.Now}")