Scope

Scope of a variable is its lifetime in the program.

The region of the program in which it can be accessed.

Local Scope

A scope can also be viewed as the space between two curly brackets - { }.

Example:

using System; class Program { static void Main(string[] args) { int num1 = 5; if (true) { int num2 = 6; Console.WriteLine(num1); Console.WriteLine(num2); } Console.WriteLine(num1); //Console.WriteLine(num2); } }

Output:

5 6 5

In this example the num1 variable can be accessed anywhere in the Main function.

The num2 variable is defined inside the if statement and can be accessed only inside it - between its curly brackets - { }.

If we uncomment line 17, it will result in an exception because num2 is accessed outside of its scope - between line 11 and line 13.

Scopes are not limited only to if statements. It's also valid for loops too.

Let's look at the following example:

using System; class Program { static void Main(string[] args) { for (int i = 0; i < 3; i++) { Console.WriteLine(i); int num = 4; Console.WriteLine(num); } // Console.WriteLine(num1); // Console.WriteLine(i); } }

Output:

0 4 1 4 2 4

In this case, both variables i and num can be accessed inside their scope - the for loop.

If we uncomment line 15 or line 16, an exception will be thrown.