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Question

What does .NET developers need to know about these certain topics?

Answer 1

+2 A:

Let me start you off.

Generics:

What is the difference between an ArrayList and a List<T>? (Boxing/unboxing should come up here).

Stu 2009-03-04 19:05:13

You gonna have to be a little more specific if you are looking for boxing. I suggest adding something like ' with regards to the item's type'. Fishing for a specific answer is not good.

leppie 2009-03-04 19:31:37

No offense, but if someone cannot point out that ArrayList forces boxing/unboxing for value types and is therefore inferior to List<valuetype>... that's exactly the kind of red flag you are looking for with this question.

Stu 2009-03-05 15:23:50

Answer 2

+3 A:

File I/O

How do you:

Read a files content
What are file encodings... e.g. UTF-8. Which encoding does .Net use internally? [Would not expect extensive detail, but should know not everything is ASCII]
Why could the following code fail with a FileNotFoundException:

if (File.Exists(name)) { var content = File.ReadAllText(name); }

Globalization

What is globalization?
What does a globalised application not have. [Should know not to hardcode user display text, date/time/number/... formats]

Richard 2009-03-04 19:16:21

For encodings: should also know which encoding .Net uses internally.

Joel Coehoorn 2009-03-04 19:26:01

Never mind: needed to edit a spelling error, so I'll add that while I'm at it.

Joel Coehoorn 2009-03-04 19:28:15

So why does the example about "File.Exists" fail? (Other than the obvious case of another thread deleting the file after the check but before the call to ReadAllText!)

Hosam Aly 2009-03-04 19:40:34

@Hosam: Two reaons: 1) Because the file system is volatile and may change in between when you check and when you use it. 2) Just because a file exists doesn't mean you have permissions to access it.

Joel Coehoorn 2009-03-04 19:41:57

[continued] The lessons is that because the file system is volatile, you have to be able to handle the exception when access to the file fails anyway, so making that exception handler work well is a much better place to put your development effort.

Joel Coehoorn 2009-03-04 19:43:44

@Joel: yes, now for more difficult questions :-)

Richard 2009-03-04 19:52:36

@Joel: The first reason is certainly true, but the second one doesn't seem so IMHO. According to the documentation of File.Exists: "If the caller does not have sufficient permissions to read the specified file, no exception is thrown and the method returns false regardless of the existence of path."

Hosam Aly 2009-03-05 04:17:34

Answer 3

+4 A:

Another for generics.

What is the proper syntax (VB or C#) to require that the passed generic type be a type that implements a specific interface?

C# Example with an interface requirement of IHydratable

public static T HydrateObject<T>(IDataReader reader) where T : IHydratable

Mitchel Sellers 2009-03-04 19:17:18

Answer 4

+2 A:

On top of my head, for junior developers:

Difference between method overriding and overloading
Difference between namespace, class, assembly
Value and reference type differences
Explain boxing and how to avoid it

muerte 2009-03-04 19:24:41

Answer 5

+1 A:

Whats Wrong with the following code

struct MyStruct
{

   int _a;
   int _b;

   public MyStruct()
   {

   }

public MyStruct(int a,int b)
   {
        _a = a;
        _b = b;
   } 

}

Oscar Cabrero 2009-03-05 19:28:53

You can't have a parameterless default constructor in a struct.

dotnetdev 2009-04-15 14:45:09

that's correct,but you can change the IL and have one

Oscar Cabrero 2009-04-16 00:11:28

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