What is Constant:
Like a Variable, Constant refer to fixed values that the Program may not change the values during its execution. This fixed values is also known as Literals. Constants can be any of the basic data types like an Integer constant, A Floating constant or a character constant. The Constant are treated just like regular variables, except that their values can't be modified after their definition.
Defining Constants:
We can define the constants using the const Keyword. The Syntax is:
const < Data_type > <Constant_name> = 18;
Let's have an example to know, how this const keyword work.
/*Example: Constant In C#: InfoBrother: */
using System;
namespace Constant
{
class Program
{
static void Main(string[] args)
{
const double PI = 3.14159; //constant declare:
double rad;
Console.WriteLine("Enter the Radius: ");
rad = Convert.ToDouble(Console.ReadLine()); //convert double to string format.
double Area_Circle = PI * rad * rad; //Formula : Area = PI *R^2.
Console.WriteLine("The Area of Circle is: " + Area_Circle);
Console.ReadKey();
}
}
}
Const Example:
Enter the Radius:
6
The Area of Circle is: 113.09724
Character Constants:
Character Literals are single Unicode character and enclosed in single Quotes. For Example, 'x' and can be stored in a Simple variable of char type. A Character literal can be plain character like 'x' and escape Sequence like '\t', or a universal character such as '\u02c0'.
There are certain characters in C# when they are preceded by a Backslash. they have special meaning and they are used to represent like newline (\n) or tab (\t). Here is a list of some escape sequence codes:
| Escape Sequence | Meaning |
|---|---|
| \\ | Use to Represent ( \ ) Backslash character. |
| \' | Use to Represent ( ' ) Single Quote. |
| \" | Use to Represent ( " ) Double Quote. |
| \? | use to Represent ( ? ) Question Mark. |
| \a | Use to get Alert or Bell. |
| \b | Use to get Backspace. |
| \f | Use to get Form Feed. |
| \n | Use to get Newline. |
| \r | Use to get Carriage Return. |
| \t | Use to get Horizontal Tab. |
| \v | Use to get Vertical Tab. |
| \0 | Use to Represent Null |
| \xhxxxx | Use to Represent Hexadecimal number of one or more digits. |
| \uxxxx | Use to represent Character corresponding to its Unicode number. |
Integer Literals:
Integer Literal can Store Numeric value. They can be decimal, octal or hexadecimal type. They can also have a sign, prefix or suffix. An integer literal can also have a suffix that is a combination of U and L, for unsigned and long, respectively. The suffix can be Uppercase or lowercase and can be in any order.
/*Example: */
85 // decimal
0x4b // hexadecimal
30 // int
30u // unsigned int
30l // long
30ul // unsigned long
Floating Point Literals.
A Floating point literal has an integer part, a decimal point, fractional part, and an exponent part. We can represent floating point literals either in decimal form or exponential form.
/*Example: */
3.14159 // Legal
314159E-5F // Legal
510E // Illegal: incomplete exponent
210f // Illegal: no decimal or exponent
.e55 // Illegal: missing integer or fraction
Boolean Literal:
Boolean Literal can store two values, true and False. Boolean data type is used to store these values.
/*Example: */
bool condition = true;
String Literal:
String Literals are set of character enclosed between double Quotes ( "" ) or ( @"" ). They can store characters or escape sequences. Strings initialized using ( @"" ) are known as verbatim string. Escape sequences does not work in verbatim string. Lines can be broke down to small lines by just using blank space.
/*Example: */
"string literal" //Output: string literal
@"string literal" //Output: string literal
"string \t literal" //Output: string literal
"string //string
literal" //literal
""Hi"" //"Hi"
Null Literal:
Null Literal denotes Null type. We can use it to denote that nothing is referenced to the NULL constant or variable.
int a = null;
if (a == null)
{
Console.WriteLine("null value");
}
