An array is a vector in a collection

To declare an array we use :
```csharp
public static void Main() {
	int[] vect = new int[4] // Declare a vector of 4 elements (from 0 to 3)
	vect[3] = 22;
	Console.WriteLine($"b = {b}");
	Console.WriteLine($"{vect[3]}");
}
```

The result will be:
```bash
b = 0
22
```

We see that an array start from $0$ to $n-1$