C# System.NullException convert null to blank or no value

Question

When using the following method there are use cases where one of the parameters, for this example RC_2 (datetime) may pass a null value. I need to have that null value converted into either a blank value or a string value so that it can be passed to a stringbuilder below is what I'm currently using,

    public static string CHG_FixDatetime(string RC_1, string RC_2, string seperator)
    {
        var sb = new StringBuilder();
        sb.Append(RC_1);
        sb.Append(RC_2);
        sb.Append(seperator);
        DateTime dt;

        if (!string.IsNullorWhiteSpace(RC_2))
          sb.append(RC_2)
        else
         {
            sb.Append(Convert.ToString(RC_2));
         }


        return sb.ToString();
    }

I've tried multiple configurations and variations, but I'm unable to get past the System.NullException that is thrown when the RC_2 value is Null. Any help is appreciated.

Why are you converting RC_2 to string? It's already a string. Also, the DateTime dt is never used. Where is the error actually occurring? — Steve, May 28 '15 at 06:14
I vote to close as a typo - you so `sb.Append(RC_2)` before your `if (!string.IsNullorWhiteSpace(RC_2))` check - no point checking after you've already used it! — John3136, May 28 '15 at 06:16
@Stevejustnow Are you claiming that appending `null` to a string won't cause an NPE? I used to assume .NET was smart enough to handle null args, but it isn't ;-) — John3136, May 28 '15 at 06:19
if the value being appended is `null` no changes are made to the `StringBuilder` instance. No `exceptions` at all. — Amit Kumar Ghosh, May 28 '15 at 06:21
@ohn3136 the `null` is being appended to a `StringBuilder`, not a `string`. — Amit Kumar Ghosh, May 28 '15 at 06:22
The whole `if`/`else` can be replaced by `sb.Append(RC_2);` - no exception thrown if `RC_2` is null (or whitespace). — Corak, May 28 '15 at 06:22
`"" + null` and `null + ""` work without throwing an exception. And even `string value = null; var other = value + value;` will result in `other` being `""` (`string.Empty`) and *not* `null`. -- See also http://ericlippert.com/2013/06/17/string-concatenation-behind-the-scenes-part-one/ — Corak, May 28 '15 at 06:29

score 0 · Answer 1 · answered May 28 '15 at 06:18

0

Try the following solution

RC_2 = String.IsNullOrWhiteSpace(RC_2) ? "" : RC_2;

answered May 28 '15 at 06:18

PaulShovan

2,140
1
13
22

C# System.NullException convert null to blank or no value

1 Answers1