Error while creating an OS in cosmos

Question

I'm creating an OS in cosmos ( C# ) , but I cannot get the code right. Here it is:

var input = Console.ReadLine();
if (input = 'h')
    Console.Write("This is the help section...");
else
    Console.Write("Invalid Command.");
Console.WriteLine(input);

What I want it to do is that when I type in 'H' it should output the help section and when I type in something else, it should type in 'Invalid Command'.

It keeps saying 'Error: Cannot implicitly convert type 'char' to 'string'.

Full code

using System;
using System.Collections.Generic;
using System.Text;
using Sys = Cosmos.System;

namespace Dingo_OS
{
    public class Kernel : Sys.Kernel
    {
        protected override void BeforeRun()
        {
        Console.WriteLine("Thank you for trying out my OS. For any help, input /h.");
        }

        protected override void Run()
        {
            var input = Console.ReadLine();
            if (input = 'h')
                Console.Write("This is the help section...");
            else
                Console.Write("Invalid Command.");
            Console.WriteLine(input);
        }
    }
}

You are writing an 'OS' and you are having problems with this code snippet? Perhaps try 'biting off' something a wee bit smaller... — Mitch Wheat, Sep 08 '13 at 06:52

score 1 · Accepted Answer · answered Sep 08 '13 at 06:52

1

Console.ReadLine returns a string, not a single character. So you need to compare it with a string. String literals uses double quotes, not single quotes. Also, you want the equality comparison operator (==) rather than the assignment operator (=):

if (input == "h")

To be honest, if you're sufficiently inexperienced in C# that this is causing you problems, I suggest you take a step back and learn the basics of C# in a more "normal" environment (e.g. console or client apps) first, before venturing into Cosmos. I haven't done any Cosmos work myself, but I suspect there will be some pretty tricky areas, which will be made much harder by not having a solid grounding in C# first.

answered Sep 08 '13 at 06:52

Jon Skeet

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Also, he is missing one equal sign. There is = instead of == in the if statement. – Ondrej Janacek Sep 08 '13 at 06:54
@OndrejJanacek: Yes, I'd edited it for that. – Jon Skeet Sep 08 '13 at 06:54
Correct me if I am wrong but is it a good practice to compare the string with == instead of .Equals??? – Rahul Tripathi Sep 08 '13 at 06:57
@RahulTripathi: Yes, that's fine so long as both operands are strings at compile-time - the `==` operator is overloaded in C#. – Jon Skeet Sep 08 '13 at 06:58
@JonSkeet:- Ok got your point. Thanks!!! – Rahul Tripathi Sep 08 '13 at 06:59
Thanks! It works now, and yeah, you're right about the C# thing. Please let me know if you find any good tutorials. – Danish Humair Sep 08 '13 at 08:44
@DanishHumair: I would suggest buying a good introductory book, to be honest. The latest edition of Head First C# is pretty good, C# in a Nutshell, or Effective C#. – Jon Skeet Sep 08 '13 at 08:46

score 0 · Answer 2 · answered Sep 08 '13 at 06:56

Console.ReadLine returns a string not a char, you can use Console.ReadKey().KeyChar for reading char

protected override void Run()
{
    var input = Console.ReadKey().KeyChar;
    if (input == 'h')
        Console.Write("This is the help section...");
    else
        Console.Write("Invalid Command.");
    Console.WriteLine(input);
}

Error while creating an OS in cosmos

2 Answers2