Question

Constants and Literals

In C# , you can declare constants for all data types. You have to initialize a constant constant at the time of its declaration. Constants are declared for value types rather than for reference  types. To declare an identifier as a constant, the const keyword is used in the identifier declaration. The compiler can identify constants at the time of compilation because of the const keyword.

Syntax:

const <data type> <identifier name> =  <value>;

Where,

const: keyword denoting that the identifier is declared as const.

Data type: Data type of constant.

Identifier name: Name of the identifier that will hold the constant.

Value: Fixed value that remains unchanged throughout the execution of the code.

Example:

The following code declares a constant, _pi , and a variable, radius, to calculate the area of the circle.

const float _pi = 3.14F;

float radius= 5;

float area = _pi * radius * radius;

Console.WriteLine (“Aread of the circle is “ +area);

In the above code, a constant called _pi  is assigned the value 3.14 which is a fixed value. The variable, radius, stores the radius of the circle. The code calculates the area of the circle and displays it as the output.

Using Literals

A literal is a static value assigned to variables and constants. You can define literals for any data types of C#. Numeric literals might suffix which a letter of the alphabet to indicate the data type of the leteral. This letter can be either in upper or lower case. For example, in the following declaration, string bookName = “Csharp”, Csharp is a literal assigned to the variable bookName of type string.

In C#, there are six types of literals. These are:

                                        

• Boolean Literal: Boolean literals have two values, true or false. For example,

bool val = true;

where, true: Is a Boolean literal assigned to the variable val.

 

• Integer Literal: An integer literal can be assigned to int, uint, logn or ulong data types. Suffixes for integer literals include U, L, UL or LU. U denotes uint or ulong, L denotes long. UL and LU denote ulong. For example,

long val = 53L;

where,

53L: Is an integer literal assigned to the variable val.

 

• Real Literal: A real literal is assigned to float, double (default), and decimal data types. This is indicated by the suffix letter appearing after the assigned value. A real literal can be suffixed by F, D or M. F denotes float, D denotes double and M denotes decimal. For example,

float val = 1.66F;

Where,

1.66F: Is a real literal assigned to the variable val.

 

• Character Literal: A character literal is assigned to a char data type. A character literal is always enclosed in single quotes. For example,

Char val = ‘A’;

Where,

A: Is a character literal assigned to the variable val.
 

• String Literal: There are two types of string literal in c#, regular and verbatim. A regular string literal is a standard string . A verbatim string literal is similar to a regular string literal but is prefixed by the @ character. A string literal is always enclosed in double quotes. For example,

string mailDomain = “@gmail.com”;

Where,

@gmail.com: Is a verbatim string literal.

Null Literal: The null lieteral has only one value, null. For example,

string email = null;

Where,

Null: specifies that email does not refer to any objects (reference).