Question

How to pass optional parameters to a method in C#?

Suppose I created one method called SendCommand

public void SendCommand(string command,string strfileName)
{
            
    if (command == "NLST *" ) //Listing Files from Server.
    {
        //code
    }
    else if (command == "STOR " + Path.GetFileName(uploadfilename)) //Uploading file to Server
    {
        //code
    }
    else if ...
}

Now I want to call this method in main method like

SendCommand("STOR ", filename);
SendCommand("LIST"); // In this case i don't want to pass the second parameter

How to achieve that?

Answer 1

Use the params attribute:

public void SendCommand(String command, params string[] strfilename)
{
}

then you can call it like this:

SendCommand("cmd");
SendCommand("cmd", "a");
SendCommand("cmd", "b");

or if you use C# 4.0 you can use the new optional arguments feature:

public void SendCommand(String command, string strfilename=null)
{ 
   if (strfilename!=null) .. 
}