C#/.NET VisualStudio, namespace problem-CodePudding

I have started learning C#/.NET/VisualStudio (2022) and have this strange problem; all the methods/classes in System and it's nested namespaces seem to be available without full path or using directives at beginning.

E.g. the following example compiles just fine:

// Program.cs
namespace MyApp
{
    internal class Program
    {
        static void Main()
        {
            Console.WriteLine("Hello World!"); //System.Console
        }

        static HttpClient client = new HttpClient(); //System.Net.Http.HttpClient
    }
}

Why this happens and can I disable this behavior somehow?

CodePudding user response：

If you are using .NET 6, this is likely from a new feature called "Implicit Usings". Depending on your project type, certain namespaces are automatically included. For example, the default console app template implicity includes the following namespaces:

System;
System.IO;
System.Collections.Generic;
System.Linq;
System.Net.Http;
System.Threading;
System.Threading.Tasks;

You can disable this feature by including the following in your project file:

<PropertyGroup>
   <ImplicitUsings>disable</ImplicitUsings>
</PropertyGroup>

There is further documentation on this feature and "Global Usings" in this Microsoft documentation.

CodePudding user response：

You are using implicit global usings. Change the lines in your .csproj files from

<ImplicitUsings>enable</ImplicitUsings>

<ImplicitUsings>disable</ImplicitUsings>