Technical interview questions


It always surperises me how simple some of these questionare – often I get asked theses:

  1. What is the difference in Sql Server when deleting all records in a table using delete or trucate.
    Simply put if one uses truncate on a table any auto-increament fields in the table are set to  the initail value – 0, and the deleted data is lost forever as the deleted rews are not recorderd in the back up log. A trucate will fail if there is any table with a foreign key referencing any row in the table truncated. Applying sql delete each deleted row is recorded in the back up log and can be recovered.
  2. What is the difference between a struct and class in C#.
    An struct is a value type, and once created the instanance of is immutable (its a value type). A struct can not be inherited but can implement an interface.

Relatively simple – now for something that really show ones knowledge

  • Now this question is what I like. You have a delegate that accepts an int and returns a integer; The delegate has three functions assigned to its invocation list.  The funtions have been assigned inside a simple method which has a local int variable x initialised to the value of 2.
  • The functions on the delegates invocation list, in order of assignment are:
    1. multiply the input value by 2 and return the result
    2. add 7 to the local x varaible and multiply the input value by 3 returning the input value
    3. substrct the input value from the local varible x and return the input value multiplied by 2
  • The delgate is called with the local variable x what is the result and why ?

The answer is 6.

Why, I’ll explain later but simply put the input value is closed i.e. the delegate acts like a closure.

Now back to Seria A which has been neglected due to work offers and answering techincal questions like 1 & 2.

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