Browse questions answered by Jon Skeet

Most appropriate data type to use?

I am creating a C# forms application and on that application needs to be an input box of some sort for users to type in a time in the format hh:mm:ss. This also needs to be able...

If you're happy to take a dependency on a 3rd party library, I'd suggest using the date/time library I maintain: Noda Time. Unlike the .NET framework, it has a type specifically for a "time without a date" - LocalTime. You can use a... more 10/29/2013 4:50:47 PM

Destination file blank after writing with StreamWriter C#

I have written a console application that in itself is working as I would like it to. It's main output works great in console. But the results inside the loop I want written to a...

When I run that code, I see an exception: Unhandled Exception: System.UnauthorizedAccessException: Access to the path 'c:\Test.txt' is denied. It's not clear how you're running this, but if it's configured as a console app and you run... more 10/29/2013 4:21:35 PM

Pass few elements to methods

I've few methods which acept collections of fixed size (e.g. 2, 3, 5). And I can't decide which way is better: public void Foo(IEnumerable<Object> objects) { ...

The second is much better in my view: It's obvious from the signature that it's expecting 3 values Failures are flagged at compile time instead of execution time more 10/29/2013 2:04:06 PM

Defining type and property of that type inside the class

There is a problem to name property and type. Example: public class A { public class B { ... } public B B; // << error } Question 1: Why error? I could solve it...

Question 1: Why error? You've got two members both called B within the same class. (A type is a member too.) You can't do that, aside from method overloading. From section 10.3 of the C# spec: The names of constants, fields,... more 10/29/2013 10:23:30 AM

Get the value from list

I create the list like var list = new List<KeyValuePair<string, string>>(); list.Add(new KeyValuePair<string, string>("1", "abc")); list.Add(new...

It sounds like you just want: var value = list.First(x => x.Key == input).Value; That's if you're sure the key will be present. It's slightly trickier otherwise, partly because KeyValuePair is a struct. You'd probably want: var pair... more 10/29/2013 10:14:41 AM

What does "///<exclude/>" mean?

I have inherited a bunch of C# code. For a couple of method definitions I find ///<exclude/> as the only XMLDoc in front of it. I tried to Google the meaning of that but...

In NDoc at least, it means that the XML documentation for this member should be excluded. From the documentation: The <exclude/> tag directs NDoc to exclude the current item from documentation. It's not clear to me whether this... more 10/29/2013 8:46:41 AM

Invalid character constant JSON

public class Test { public static void main(String[] args) throws ClientProtocolException, IOException { HttpClient client = new DefaultHttpClient(); JSONObject json...

If this is meant to be Java, you want: json.put("set_boot", true); json.put("synchronous", true); (There are similar problems later on.) Note: String literals are in double-quotes, not single-quotes in Java You're calling a method... more 10/29/2013 7:28:11 AM

How does overload resolution work with a null argument?

Why is the method with a parameter of type Object[] called rather than the method with a parameter of type Object when null is passed as the argument? class Demo { void...

Firstly, it's important to note that the null value is convertible to both Object and Object[], so both methods are applicable. Then it's just a matter of overload resolution. That's described in section 15.12 of the JLS, and section... more 10/29/2013 7:22:15 AM

Generating fatal error in Java

Suppose we are writing a Java library, which provides some I/O ulitity functions, for example, a convenient method to read text files as Strings: public class StringReader...

But what if it doesn't? Then you're in a really bad situation, and you should probably get out of it as quickly as possible. When a JRE is violating its own promises, what would you want to depend on? I'd feel happy using... more 10/29/2013 7:04:56 AM

Linq Query Distinct Function do not work with DropdownList

I want to assign Linq Query result to dropdownlist which contain a Distinct function My Code:- var area = de.City_Area_View .Select(m => new {...

If your set is small enough (so you don't mind fetching all the values from the database), the simplest thing would be to force the distinct part to be performed locally: var area = de.City_Area_View .Select(m => new {... more 10/29/2013 7:01:24 AM