Question

I have Form1 and class in file called AbstractClass.cs.

I want to call a label in Form1 and assign msg string to the text in that lable.

How can I do that???

here is my class.

//"Concrete CPUMoon" drived from AbstractCPU class when Diagnosticing CPU for Moon system
class CPUMoon : AbstractCPU
{
    public override void DisplayName(AbstractCPU a)
    {
        //Form1 f1 = new Form1();

        string msg;
        // create reader & open file
        StreamReader tr = new StreamReader("Moon.txt");
        String fromFile = tr.ReadLine();
        // close the stream
        tr.Close();
        msg = "CPU diagnosing has be done for   " + a.GetType().Name + "                " + fromFile;
        //Console.WriteLine("CPU diagnosing has be done for   " + a.GetType().Name + "                //" + fromFile);
    }
}

Answer 1

All You need is a Property in your class and then call this property from the class like

   public class AnyCLass
   {
       public string Message{get; set;}
       // any other methods or properties in class ...
       // note thatin any method which you change the Message content it should be 
       // used and if you do not call the method which change the Message value ,
       // you have a string.Empty value
       // to test this change the Message Value in Constructor like below

       public AnyClass()
       {
          this.Message = "You have to change the value somewhere which call with user";
       }
   }

   public partial class Form1.cs
   {
       AnyClass instance = new AnyClass();
       Label1.Text = instance.Message;
   }