C# Variable Scope

In C#, the scope of a variable refers to where in the code that variable is accessible.

Variables can have three levels of scope in C#: class level, method level, and block level.

In this article, we'll take a look at each level of scope and provide some examples.

Class Level Scope

A variable that is declared at the class level can be accessed from any method or block within that class. Here's an example:

1public class MyClass
2{
3    private string name = "William";
4
5    public void SayHello()
6    {
7        Console.WriteLine("Hello, " + name + "!");
8    }
9
10    public void ChangeName(string newName)
11    {
12        name = newName;
13    }
14}

In this example, the name variable is declared at the class level, so it can be accessed from both the SayHello and ChangeName methods.

Method Level Scope

A variable that is declared within a method can only be accessed within that method. Here's an example:

1public void MyMethod()
2{
3    int x = 10;
4    Console.WriteLine(x);
5}

In this example, the x variable is declared within the MyMethod method, so it can only be accessed within that method.

Block Level Scope

A variable that is declared within a block (i.e., a set of braces) can only be accessed within that block. Here's an example:

1public void MyMethod()
2{
3    int x = 10;
4
5    if (x == 10)
6    {
7        string message = "x is 10";
8        Console.WriteLine(message);
9    }
10
11    // This will not compile, as message is out of scope
12    // Console.WriteLine(message);
13}

In this example, the message variable is declared within the if block, so it can only be accessed within that block.