C# - Variables

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Variables are the fundamental of all programming languages. Variables are used to store data such as strings of text, integers, and so on. The variables' data or values can be set, modified, and retrieved as needed.

C# supports a wide range of different data types for variables.

bool - stores a Boolean value (true or false)
byte - stores an 8-bit unsigned integer
short - stores a 16-bit signed integer
int - stores a 32-bit signed integer
long - stores a 64-bit signed integer
float - stores a single-precision floating-point number
double - stores a double-precision floating-point number
decimal - stores a decimal number with higher precision than a double
char - stores a single Unicode character
string - stores a sequence of Unicode characters

C# Variable Nameing Conventions

Variable names are case-sensitive in C#. So, the variable names msg, Myvar, myVar, MyVar are considered separate variables.
Variable names can contain letters, digits, or the symbols underscore _ only.
A variable name cannot start with a digit 0-9.
A variable name cannot be a reserved keyword in C# such as int or double cannot be variable names.

To declare a variable in C#, you need to specify its data type and give it a name.

string myTextname = "Rohatash";
int myNum = 5;
double myDoubleNum = 5.99D;
char myLetter = 'D';
bool myBool = true;

C# Variable with Constant Keyword

This will declare the variable as "constant", which means unchangeable and read-only. The const keyword is useful when you want a variable to always store the same value.

Example

const int myNum = 30;
myNum = 15; // error

C# Multiple Variables

When you want to declare more than one variable of the same type, use a comma-separated list.