Technical Tips, Tricks and Articles

Interview Questions (.NET)

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  1. What’s the difference of using System.Text.StringBuilder over System.String?
    Answer: System.String is immutable. System.StringBuilder was designed with the
    purpose of having a mutable string where a variety of operations can be performed.

  2. What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?
    The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements
    into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element’s object, resulting in a different, yet identical object.

  3. How can you sort the elements of the array in descending order?
    Answer: By calling Sort () and then Reverse () methods.

  4. What’s the .NET collection class that allows an element to be accessed using a unique key?
    Answer: Hashtable.

  5. Can you allow a class to be inherited, but prevent the method from being over-ridden?
    Answer: Yes. Just leave the class public and make the method sealed.

  6. When do you absolutely have to declare a class as abstract?
    1. When the class itself is inherited from an abstract class, but not all base abstract methods have been overridden.
    2. When at least one of the methods in the class is abstract.
  7. What accessibility modifier for methods you may specify inside the interface?
    They all must be public, and are therefore public by default.
  8. What’s the implicit name of the parameter that gets passed into the set method/property of a class?
    Value. The data type of the value parameter is defined by whatever data type the property is declared as.
  9. What’s the difference between // comments, /* */ comments and /// comments?
    // is single-line comment, /**/ is multi-line comment & /// is document comment
  10. What is CorDBG and what is DbgCLR?
    Cordbg is a runtime debugger.
  11. What does assert() method do?
    In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true.
  12. What’s the difference between the Debug class and Trace class?
    Documentation looks the same. Use Debug class for debug builds, use Trace class for both debug and release builds.
  13. What happens if you inherit multiple interfaces and they have conflicting method names?

    Answer: It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay. You have to provide interfacename.methodname.

Written by ..alee

December 16, 2006 at 3:49 pm

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