C# Variables

C# Variables

Variables in C# are used to store data that can be used and changed during program execution.

 What is a Variable?

A variable is a named memory location that holds a value.

int age = 25;

  • int → data type

  • age → variable name

  • 25 → value

 Declaring Variables



 

Or declare and assign together:



 

 Common Data Types

Data Type Description Example
int Integer numbers int x = 5;
double Decimal numbers double pi = 3.14;
float Decimal (less precision) float temp = 36.5f;
char Single character char grade = 'A';
string Text string name = "Vipul";
bool True/False bool isActive = true;

 Multiple Variable Declaration



 

 Constants

A constant value cannot be changed.



 

 Variable Naming Rules

✔ Must start with a letter or _
✔ Cannot start with a number
✔ Cannot use C# keywords
✔ Case-sensitive



 

 Type Inference (var)

The compiler automatically detects the type.



 

⚠ var variables must be initialized.

 Changing Variable Values



 

 Output Variables



 

 Summary

✔ Variables store data
✔ Must have a data type
✔ Values can be changed
✔ const is used for fixed values
✔ var simplifies declarations

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