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Variable in C#

In computer programming, a variable is a named storage location that holds a value of a specific type. It allows you to store and manipulate data within your program. Variables provide a way to refer to and work with data throughout your code.

Here's an example of how to define a variable in C#: 


int age; // Declaration
age = 25; // Initialization
In this example, we declared a variable named age of type int (integer). The variable is declared but not yet assigned a value. Later, we initialized the age variable with the value 25 using the assignment operator (=).

Once a variable is declared and initialized, you can use its value in your program. For example, you can display it on the console: 


Console.WriteLine("Age: " + age);

This code will output: 


Age: 25

You can also perform calculations using variables: 


int birthYear = 1998;
int currentYear = 2023;
int age = currentYear - birthYear;

Console.WriteLine("Age: " + age);

The output will be: 


Age: 25

In this example, we declared three variables: birthYear, currentYear, and age. We assigned values to birthYear and currentYear, and then calculated the age by subtracting birthYear from currentYear. Finally, we displayed the calculated age on the console.

Variables in C# can have different types, such as int, string, double, bool, and many more. The type determines the kind of data that can be stored in the variable and the operations that can be performed on it.

C# is a statically typed language, which means you need to specify the type of a variable at compile-time. However, C# also supports type inference through the var keyword, allowing the compiler to automatically determine the variable type based on the assigned value.

Here's an example of using var for type inference: 


var message = "Hello, world!";

In this case, the compiler infers that message is of type string based on the assigned value.

Remember to choose appropriate variable names that reflect the purpose or meaning of the data they store.

@ symbol in front of a variable name

In C#, when you see the @ symbol in front of a variable name, it is used as a verbatim identifier or verbatim string literal.

Verbatim Identifier:
In C#, the @ symbol can be used as a prefix to indicate a verbatim identifier. It allows you to use reserved keywords as variable names. For example: 


int @int = 10; // Using "int" as a variable name by prefixing with @

In this case, @int is a valid variable name that can be used to declare an integer variable. Without the @ symbol, int would be considered a reserved keyword and not a valid variable name.

Verbatim String Literal:
The @ symbol can also be used to create a verbatim string literal. It allows you to include special characters, line breaks, and escape sequences within the string without any interpretation. For example: 


    string filePath = @"C:\Folder\file.txt"; // Verbatim string literal

In this case, the @ symbol before the string "C:\Folder\file.txt" makes it a verbatim string literal. The backslashes are not treated as escape characters, which is useful when dealing with file paths or regular expressions.

It's important to note that using the @ symbol as a prefix does not change the behavior or type of the variable itself. It simply allows you to use reserved keywords as identifiers or to create verbatim string literals without escaping special characters.

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