How to do ToString for a possibly null object?

Question

Is there a simple way of doing the following:

String s = myObj == null ? "" : myObj.ToString();

I know I can do the following, but I really consider it as a hack:

String s = "" + myObj;

It would be great if Convert.ToString() had a proper overload for this.

Answer 1

string.Format("{0}", myObj);

string.Format will format null as an empty string and call ToString() on non-null objects. As I understand it, this is what you were looking for.

Answer 2

actually I didnt understand what do you want to do. As I understand, you can write this code another way like this. Are you asking this or not? Can you explain more?

string s = string.Empty;
    if(!string.IsNullOrEmpty(myObj))
    {
    s = myObj.ToString();
    }

Answer 3

With an extension method, you can accomplish this:

public static class Extension
{
    public static string ToStringOrEmpty(this Object value)
    {
        return value == null ? "" : value.ToString();
    }
}

The following would write nothing to the screen and would not thrown an exception:

        string value = null;

        Console.WriteLine(value.ToStringOrEmpty());

Answer 4

String s = (myObj ?? String.Empty).ToString();

or

String s = (myObjc ?? "").ToString()

to be even more concise.

Edit: As has been pointed out you'll often need a cast on either side to make this work with non String or Object types:

String s = (myObjc ?? (Object)"").ToString()
String s = ((Object)myObjc ?? "").ToString()

Answer 5

I disagree with that this:

String s = myObj == null ? "" : myObj.ToString();

is a hack in any way. I think it's a good example of clear code. It's absolutely obvious what you want to achieve and that you're expecting null.

UPDATE:

I see now that you were not saying that this was a hack. But it's implied in the question that you think this way is not the way to go. In my mind it's definitely the clearest solution.

Answer 6

Holstebroe's comment would be your best answer:

string s = string.Format("{0}", myObj);

If myObj is null, Format places an Empty String value there.

It also satisfies your one line requirement and is easy to read.

Answer 7

I might get beat up for my answer but here goes anyway:

I would simply write

string s = "" if (myObj != null) { x = myObj.toString(); }

Is there a payoff in terms of performance for using the ternary operator? I don't know off the top of my head.

And clearly, as someone above mentioned, you can put this behavior into a method such as safeString(myObj) that allows for reuse.

Answer 8

string s = String.Concat(myObj);

would be the shortest way I guess and also have neglible performance overhead. Keep in mind though it wouldn't be quite clear for the reader of the code what the intention is.