Interview - 3

Front 1

What is the difference between public, static and void?

Back 1

All these are access modifiers in C#. Public declared variables or methods are accessible anywhere in the application. Static declared variables or methods are globally accessible without creating an instance of the class. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created. And Void is a type modifier that states that the method or variable does not return any value.

Front 2

What is an object.

Back 2

An object is an instance of a class through which we access the methods of that class. “New” keyword is used to create an object. A class that creates an object in memory will contain the information about the methods, variables and behavior of that class.

Front 3

Define constructors

Back 3

A constructor is a member function in a class that has the same name as its class. The constructor is automatically invoked whenever an object class is created. It constructs the values of data members while initializing the class

Front 4

What is the difference between ref & out parameters?

Back 4

An argument passed as ref must be initialized before passing to the method whereas out parameter needs not to be initialized before passing to a method.

Front 5

What is the use of using statement in C#?

Back 5

The using block is used to obtain a resource and use it and then automatically dispose of when the execution of block completed.

Front 6

What is serialization?

Back 6

When we want to transport an object through network then we have to convert the object into a stream of bytes. The process of converting an object into a stream of bytes is called Serialization. For an object to be serializable, it should inherit ISerialize Interface.
De-serialization is the reverse process of creating an object from a stream of bytes.

Front 7

Can “this” be used within a static method?

Back 7

We can’t use ‘This’ in a static method because we can only use static variables/methods in a static method.

Front 8

What is difference between constants and read-only?

Back 8

Constant variables are declared and initialized at compile time. The value can’t be changed after wards. Read-only variables will be initialized only from the Static constructor of the class. Read only is used only when we want to assign the value at run time.

Front 9

What are value types and reference types?

Back 9

Value types are stored in the Stack whereas reference types stored on heap.
Value types:
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int, enum , byte, decimal, double, float, long
Reference Types:
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string , class, interface, object.

Front 10

What are Custom Control and User Control?

Back 10

Custom Controls are controls generated as compiled code (Dlls), those are easier to use and can be added to toolbox. Developers can drag and drop controls to their web forms. Attributes can be set at design time. We can easily add custom controls to Multiple Applications (If Shared Dlls), If they are private then we can copy to dll to bin directory of web application and then add reference and can use them.
User Controls are very much similar to ASP include files, and are easy to create. User controls can’t be placed in the toolbox and dragged – dropped from it. They have their design and code behind. The file extension for user controls is ascx.

Front 11

What is the difference between Array and Arraylist?

Back 11

In an array, we can have items of the same type only. The size of the array is fixed. An arraylist is similar to an array but it doesn’t have a fixed size.

Front 12

What is the difference between Finalize() and Dispose() methods?

Back 12

Dispose() is called when we want for an object to release any unmanaged resources with them. On the other hand Finalize() is used for the same purpose but it doesn’t assure the garbage collection of an object.

Front 13

What are circular references?

Back 13

Circular reference is situation in which two or more resources are interdependent on each other causes the lock condition and make the resources unusable.

Front 14

What are generics in C#.NET?

Back 14

Generics are used to make reusable code classes to decrease the code redundancy, increase type safety and performance. Using generics, we can create collection classes. To create generic collection, System.Collections.Generic namespace should be used instead of classes such as ArrayList in the System.Collections namespace. Generics promotes the usage of parameterized types.

Front 15

What is an object pool in .NET?

Back 15

An object pool is a container having objects ready to be used. It tracks the object that is currently in use, total number of objects in the pool. This reduces the overhead of creating and re-creating objects.

Front 16

List down the commonly used types of exceptions in .Net?

Back 16

ArgumentException, ArgumentNullException , ArgumentOutOfRangeException, ArithmeticException, DivideByZeroException ,OverflowException , IndexOutOfRangeException ,InvalidCastException ,InvalidOperationException , IOEndOfStreamException , NullReferenceException , OutOfMemoryException , StackOverflowException etc.

Front 17

What are Custom Exceptions?

Back 17

Sometimes there are some errors that need to be handeled as per user requirements. Custom exceptions are used for them and are used defined exceptions.

Front 18

What are delegates?

Back 18

Delegates are same are function pointers in C++ but the only difference is that they are type safe unlike function pointers. Delegates are required because they can be used to write much more generic type safe functions.

Front 19

What is difference between is and as operators in c#?

Back 19

“is” operator is used to check the compatibility of an object with a given type and it returns the result as Boolean.

Front 20

How we can create an array with non-default values?

Back 20

We can create an array with non-default values using Enumerable.Repeat.

Front 21

What’s a multicast delegate?

Back 21

A delegate having multiple handlers assigned to it is called multicast delegate. Each handler is assigned to a method.

Front 22

What are indexers in C# .NET?

Back 22

Indexers are known as smart arrays in C#. It allows the instances of a class to be indexed in the same way as array.
Eg:
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public int this[int index] // Indexer declaration

Front 23

What is difference between the “throw” and “throw ex” in .NET?

Back 23

“Throw” statement preserves original error stack whereas “throw ex” have the stack trace from their throw point. It is always advised to use “throw” because it provides more accurate error information.

Front 24

What are C# attributes and its significance?

Back 24

C# provides developers a way to define declarative tags on certain entities eg. Class, method etc. are called attributes. The attribute’s information can be retrieved at runtime using Reflection.

Front 25

What is the difference between directcast and ctype?

Back 25

DirectCast is used to convert the type of an object that requires the run-time type to be the same as the specified type in DirectCast.
Ctype is used for conversion where the conversion is defined between the expression and the type

Front 26

Is C# code is managed or unmanaged code?

Back 26

C# is managed code because Common language runtime can compile C# code to Intermediate language.