解析命令行参数字符串

Question

This will seem a strange question so I will explain it as simply as possible. I am making an app like CMD in C# and I need to have commands like 'ping'. I have a switch statement that checks the command entered and executes it. This is:

switch (CommandName)
{
    case "intro":
        {
            Console.WriteLine("intro");
            CommandListen();
        }
        break;

    case "clear":
        {
            CommandFolder.CmdClear cmd = new CommandFolder.CmdClear();
            cmd.Execute();
            CommandListen();
        }
        break;

    case "ping":
        {
            CommandFolder.CmdPing cmd = new CommandFolder.CmdPing();
            cmd.Execute(CommandName);
            CommandListen();
        }
        break;

    case "exit":
        {
            CommandFolder.CmdExit cmd = new CommandFolder.CmdExit();
            cmd.Execute();
        }
        break;

    default:
        CommandListen();
        break;
}

I have no idea how to get it to work with parameters for a command, ie ping [ip/url] [extra]. If I enter 'ping' it works and executes the command, but if I enter 'ping www.google.com' it comes up with my unrecognized command error. I need a way to check the first part of the command, and then pass the parameters through.

I apologize if this is vague, I just didn't know how to word it.

Answer 1

You need to define a syntax and write a parser for that. As @Lasse and @Dan suggested in the comments, it can be as simple as "a command and its parameters are separated by one space", which will make a naive implementation of the parsing code look like this:

string commandParts = CommandName.Split(" ");
string commandName = commandParts[0];
var arguments = commandParts.Skip(1).ToList();

var command = new SomeCommand(arguments);

This code splits the input on space (" "), takes the first result as the command and the optional remainder as arguments (no arguments entered will become an empty arguments list).

You'll of course need to add code for error handling for when no command is entered, or adjust the split code if you want to support multiple spaces being entered.