C# Interview Questions and Answers Part 13

Difference between value and reference type. what are value types and reference types?
Value type - bool, byte, chat, decimal, double, enum , float, int, long, sbyte, short, strut, uint, ulong, ushort
Value types are stored in the Stack
Reference type - class, delegate, interface, object, string
Reference types are stored in the Heap


What are the two kinds of properties.
Two types of properties in .Net: Get and Set


Explain constructor.
Constructor is a method in the class which has the same name as the class (in VB.Net its New()). It initializes the member attributes whenever an instance of the class is created.


Describe ways of cleaning up objects.
Answer1
There is a perfect tool provide by .net frameworks calls Garbage collector, where by mean of GC we can clean up the object and reclaim the memory. The namespace used is System.GC

Answer2
the run time will maintain a service called as garbage collector. This service will take care of deallocating memory corresponding to objects. it works as a thread with least priority. when application demands for memory the runtime will take care of setting the high priority for the garbage collector, so that it will be called for execution and memory will be released. the programmer can make a call to garbage collector by using GC class in system name space.


How can you clean up objects holding resources from within the code?
Call the dispose method from code for clean up of objects


Which controls do not have events?
Timer control.


What is the maximum size of the textbox?
65536.


Which property of the textbox cannot be changed at runtime?
Locked Property.


Which control cannot be placed in MDI?
The controls that do not have events.


What is the difference between proc. sent BY VAL and BY SUB?
BY VAL: changes will not be reflected back to the variable.
By REF: changes will be reflected back to that variable.( same as & symbol in c, c++)


General C# Interview Questions :


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 identical object.


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