C# Training - Variables

Variables

In C#, variables are used to store and manipulate data. Here's how you can declare and use variables in C#:

1. Variable Declaration:
   - Syntax:
   data_type variable_name;
   - Example:
   int age;
double height;
string name;
2. Variable Initialization:
   - Syntax:
   data_type variable_name = initial_value;
   - Example:
   int age = 25;
double height = 1.75;
string name = "John";
3. Assigning Values to Variables:
   - Once a variable is declared, you can reassign a value to it using the assignment operator (=).
   - Example:
   age = 25;
height = 1.75;
name = "John";

4. Variable Naming Rules: - Variable names can consist of letters, digits, and underscores.
   - They must start with a letter or an underscore.
   - They are case-sensitive (`age` and `Age` are different variables).
   - Choose meaningful names to improve code readability.
5. Using Variables: - You can use variables in expressions, assignments, and function calls.
   - Example:
   int x = 10;
int y = 5;
int sum = x + y; // Using variables in an expression
string greeting = "Hello, " + name; // Concatenating variables in a string
Console.WriteLine(sum); // Outputting the value of a variable
6. Variable Scope:
   - Variables have a scope, which defines where they can be accessed.
   - Local variables: Declared within a method or a block and are only accessible within that scope.
   - Global variables: Declared outside any method or block and can be accessed throughout the program.
7. Constants:
   - Constants are variables whose values cannot be changed once assigned.
   - Syntax:
   const data_type constant_name = value;
   - Example:
   const double PI = 3.14159;
const int MAX_VALUE = 100;

Remember to choose appropriate data types for your variables based on the type of data they will store. Understanding variable declaration and usage is crucial for working with data in C#.

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