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.Net Programming Concepts Interview Questions and Answers for Freshers and Experience Part-3

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.net13. What is a parameter? Explain the new types of parameters introduced in C# 4.0.
A parameter is a special kind of variable, which is used in a function to provide a piece of information or input to a caller function. These inputs are called arguments. In C#, the different types of parameters are as follows:
Value type – Refers that you do not need to provide any keyword with a parameter.
Reference type – Refers that you need to mention the ref keyword with a parameter.
Output type – Refers that you need to mention the out keyword with a parameter.
Optional parameter – Refers to the new parameter introduced in C# 4.0. It allows you to neglect the parameters that have some predefined default values. The example of optional parameter is as follows:
public int Sum(int a, int b, int c = 0, int d = 0); /* c and d is optional */
Sum(10, 20); //10 + 20 + 0 + 0
Sum(10, 20, 30); //10 + 20 + 30 + 0
Sum(10, 20, 30, 40); //10 + 20 + 30 + 40
public void CreateAccount(string name, string address = “unknown”, int age = 0);
CreateAccount(“Sara”, age: 30);
CreateAccount(address: “India”, name: “Sara”);
Named parameter – Refers to the new parameter introduced in C# 4.0. Now you can provide arguments by name rather than position. The example of the named parameter is as follows:

14. Briefly explain the characteristics of reference-type variables that are supported in the C# programming language.
The variables that are based on reference types store references to the actual data. The keywords that are used to declare reference types are:
Class – Refers to the primary building block for the programs, which is used to encapsulate variables and methods into a single unit.
Interface – Contains only the signatures of methods, properties, events, or indexers.
Delegate – Refers to a reference type that is used to encapsulate a named or anonymous method.

15. What are the different types of literals?
A literal is a textual representation of a particular value of a type.
The different types of literals in Visual Basic are:
Boolean Literals – Refers to the True and False literals that map to the true and false state, respectively.
Integer Literals – Refers to literals that can be decimal (base 10), hexadecimal (base 16), or octal (base 8).
Floating-Point Literals – Refers to an integer literal followed by an optional decimal point By default, a floating-point literal is of type Double.
String Literals – Refers to a sequence of zero or more Unicode characters beginning and ending with an ASCII double-quote character.
Character Literals – Represents a single Unicode character of the Char type.
Date Literals – Represents time expressed as a value of the Date type.
Nothing – Refers to a literal that does not have a type and is convertible to all types in the type system.
The different types of literals in C# are:

Boolean literals – Refers to the True and False literals that map to the true and false states, respectively.
Integer literals – Refers to literals that are used to write values of types int, uint, long, and ulong.
Real literals – Refers to literals that are used to write values of types float, double, and decimal.
Character literals – Represents a single character that usually consists of a character in quotes, such as ‘a’.
String literals – Refers to string literals, which can be of two types in C#:
A regular string literal consists of zero or more characters enclosed in double quotes, such as “hello”.
A verbatim string literal consists of the @ character followed by a double-quote character, such as @”hello”.
The Null literal – Represents the null-type.

16. What is the main difference between sub-procedure and function?
The sub-procedure is a block of multiple visual basic statements within Sub and End Sub statements. It is used to perform certain tasks, such as changing properties of objects, receiving or processing data, and displaying an output. You can define a sub-procedure anywhere in a program, such as in modules, structures, and classes.
We can also provide arguments in a sub-procedure; however, it does not return a new value.
The function is also a set of statements within the Function and End Function statements. It is similar to sub-procedure and performs the same task. The main difference between a function and a sub-procedure is that sub-procedures do not return a value while functions do.

17. Determine the output of the code snippet.
int a = 29;
a -= ++a;
Console.WriteLine(“The value of a is: {0}”, a);

/* The output of the code is -1. */

18. Differentiate between Boxing and Unboxing.
When a value type is converted to an object type, the process is known as boxing; whereas, when an object type is converted to a value type, the process is known as unboxing.
Boxing and unboxing enable value types to be treated as objects. Boxing a value type packages it inside an instance of the Object reference type. This allows the value type to be stored on the garbage collected heap. Unboxing extracts the value type from the object. In this example, the integer variable i is boxed and assigned to object obj.
int i = 123;
object obj = i; /* Thi line boxes i. */

/* The object obj can then be unboxed and assigned to integer variable i: */
i = (int)obj; // unboxing



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