C# Variable

A variable is the name of a memory location. It is used to store data. Its value can be changed and it can be reused many times.It is a way to represent memory location through symbol so that it can be easily identified.

Variable Type	Example
Decimal types	decimal
Boolean types	True or false value, as assigned
Integral types	int, char, byte, short, long
Floating point types	float and double
Nullable types	Nullable data types

type variable_list;

//The example of declaring a variable is given below:

int i, j;  
double d;      
float f;      
char ch

//Example of veriable declartion
int i=2,j=4;  //declaring 2 variable of integer type      
float f=40.2;      
char ch='B';  

Rules for defining variables

• A variable can have alphabets, digits, and underscore.
• A variable name can start with the alphabet and underscore only. It can't start with a digit.
• No white space is allowed within the variable name.
• A variable name must not be any reserved word or keyword e.g. char, float, etc.

//Valid variable names:
int x;      
int _x;      
int k20;
//Invalid variable names:
int 4;      
int x y;      
int double;