Top General Questions
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- Does C# support multiple-inheritance?
No. - Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class). - Are private class-level variables inherited?
Yes, but they are not accessible. Although they are not visible or accessible via the class interface, they are inherited. - Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived from the specified base class. - What’s the top .NET class that everything is derived from?
System.Object. - What does the term immutable mean?
The data value may not be changed. Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory. - What’s the difference between System.String and System.Text.StringBuilder classes?
System.String is immutable. System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed. - What’s the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created. - Can you store multiple data types in System.Array?
No. - 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 identacle object. - How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods. - What’s the .NET collection class that allows an element to be accessed using a unique key?
HashTable. - What class is underneath the SortedList class?
A sorted HashTable. - Will the finally block get executed if an exception has not occurred?
Yes. - What’s the C# syntax to catch any possible exception?
A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}. - Can multiple catch blocks be executed for a single try statement?
No. Once the proper catch block processed, control is transferred to the finally block (if there are any). - Explain the three services model commonly know as a three-tier application.
Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources).
