C# tostring on null

If format is null or an empty string, the return value of this instance is formatted with the general numeric format specifier G. The return value is formatted by using the NumberFormatInfo object for the current culture. The following example displays a Decimal value using the default ToString method.

It also displays the string representations of the Decimal value that result from using a number of standard format specifiers. The ToString method formats a Decimal value in the default "G", or general format of the current culture. If you want to specify a different format or culture, use the other overloads of the ToString method, as follows:. Skip to main content.

This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. To String Method Reference Is this page helpful?

Please rate your experience Yes No. Probably the Show method handles a null value and just shows nothing. The second use of s - s. ToString fails because you there is no ToString method to run. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. ToString on null string Ask Question. Asked 10 years, 11 months ago.

Active 1 year, 6 months ago. Viewed 84k times. Why does the second one of these produce an exception while the first one doesn't? Show s ; MessageBox. Show s. ToString ; Updated - the exception I can understand, the puzzling bit to me is why the first part doesn't show an exception. MartW MartW The safe way to do- see How to do ToString for a possibly null object?

To avoid null damage on a string or object, obj?. For second line, the error happens because you invoke a method. ToString on a null string reference. This is why you get an exception. The actual dateTime object your looking to format is in the dt. Value property, and not on the dt2 object itself. You guys are over engineering this all and making it way more complicated than it really is.

Important thing, stop using ToString and start using string formatting like string. Format or methods that support string formatting like Console.

Here is the preferred solution to this question. This is also the safest. I update the examples with up to date methods of today's C compiler. Output: I put single quotes in it so you can see that it comes back as a empty string when null. As others have stated you need to check for null before invoking ToString but to avoid repeating yourself you could create an extension method that does that, something like:.

The problem with formulating an answer to this question is that you do not specify the desired output when the nullable datetime has no value. The following code will output DateTime. MinValue in such a case, and unlike the currently accepted answer, will not throw an exception.

Seeing that you actually want to provide the format I'd suggest to add the IFormattable interface to Smalls extension method like so, that way you don't have the nasty string format concatenation.

You can use dt2. ToString "format" , but of course that requires that dt2! There are several solutions here, but the big question is: How do you want to format a null date? Here is a more generic approach. This will allow you to string format any nullable value type. I have included the second method to allow overriding the default string value instead of using the default value for the value type.

The behaviour with ToString "yy Here is Blake's excellent answer as an extension method. Add this to your project and the calls in the question will work as expected. Meaning it is used like MyNullableDateTime. IFormattable also includes a format provider that can be used, it allows both format of IFormatProvider to be null in dotnet 4.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Ask Question. Asked 12 years, 1 month ago. That question is about how MessageBox.

Show and String. Concat work with null strings. Note that you're using the word "nullable" to mean two totally different things. An int? Add a comment. Active Oldest Votes. Improve this answer. So basically because it's not actually null, it's just pretending to be?

Yes, basically it's a structure wrapped around an int field and boolean sign indicating whether this structure was set to int value, or still unitialized, which mean null. Not Int? This is all correct, but also note that selectedItem. GetType will throw if Cost is null of type int? It's compiler magic. Asif Mushtaq Asif Mushtaq HasValue is false — 3Doubloons. Tom Highfield Tom Highfield 55 2 2 bronze badges. If you do this you will get your error: int?

ToString In order to check whether or not your int? Not completely true. See Nullable T. Sashi Kant Sashi Kant So what happens when we do: int? Habib Habib k 27 27 gold badges silver badges bronze badges.