Question

I have a function in a utility class

  namespace GUI.code
 {
   public class Utility
  {
     public string GetFileName(string grpID)
    {
        string filenameUNC = "\\\\" + "localhost" + "\\AgentShare\\";

        string realPath = GetPath(filenameUNC);

        return realPath;
    }
   }
  }

now i call this function from another page in the project like this:

new utility.GetCSFileName(ID);

why do i need to add new, why cant i call it like

GetCSFileName(ID);

when i have

     using GUI.code;

on top

if i remove new i get this error

Error 1 An object reference is required for the non-static field, method, or property ‘copiunGUI.code.GUIUtility.GetCSFileName(string)

any suggestions

Answer 1

You can call Utility.GetFileName() if you change the declaration to public static string GetFileName(string grpID)

static means that the member is shared among all instances of the Utility class. Remember, c# is an object-oriented language. Non-static members are called instance members, and must be called on a distinct instance of the class. Each time you call new Utility(), you are creating such an instance, and this is distinct from every other.

This is useful when each instance of a class needs to maintain information (state) internally. If, however, a particular member does not use state data — it accepts parameters, does work, and optionally returns a result — it can be declared static. Then you call it not from the instance variable but from the class name itself (in this case Utility.GetFileName().

When all of the members of a class are static, you can add static to the class declaration itself. At that point, you would never be able to call new Utility(), which might be what you want in this case.