How to use class from other files in C# with visual studio?

Question

I am a newbie of C# and MS visual studio, and I want to use the C# class which defined in another file, but can't get it work.

Here is the program.cs(and why can't I rename that file ?)

using System;  namespace TestCSharp2 {     class Program     {         static void Main(string[] args)         {             Class2 class2 = new Class2();             // here the IDE will complain that cant find namespace or balabala..             class2.setValue(10);             Console.WriteLine(class2.getValue().ToString());             Console.ReadKey();         }     } } 

And here is the Class2 that I want to use in file Class2.cs:

namespace TestCSharp2 {     class Class2     {         int i;         public void setValue(int i)         {             this.i = i;         }         public int getValue()         {             return this.i;         }     } } 

Should I #include or something? isn't use namespace enough?

---

As some guys asked if they are in the same assembly/same project, I presume they were, because here is the procedure how they are created:

• A new project using the template of Console C# Project, then the program.cs was created by default.
• The Class2.cs was created with [File] -> [New] -> [File] -> [C# class] and saved in the same folder where program.cs lives.

To be honest, I don't know if they are in same assembly / same project, but I guess they were.

Answer 1

According to your explanation you haven't included your Class2.cs in your project. You have just created the required Class file but haven't included that in the project.

The Class2.cs was created with [File] -> [New] -> [File] -> [C# class] and saved in the same folder where program.cs lives.

Do the following to overcome this,

Simply Right click on your project then -> [Add] - > [Existing Item...] : Select Class2.cs and press OK

Problem should be solved now.

Furthermore, when adding new classes use this procedure,

Right click on project -> [Add] -> Select Required Item (ex - A class, Form etc.)