Page 103 - CSharp/C#

Array covariance

string[] strings = new[] {"foo", "bar"};
object[] objects = strings; // implicit conversion from string[] to object[]

This conversion is not type-safe. The following code will raise a runtime exception:

string[] strings = new[] {"Foo"};
object[] objects = strings;

objects[0] = new object(); // runtime exception, object is not string
string str = strings[0]; // would have been bad if above assignment had succeeded

Getting and setting array values

int[] arr = new int[] { 0, 10, 20, 30};

// Get
Console.WriteLine(arr[2]); // 20

// Set
arr[2] = 100;

// Get the updated value
Console.WriteLine(arr[2]); // 100

Declaring an array

An array can be declared and filled with the default value using square bracket ([]) initialization
syntax. For example, creating an array of 10 integers:

int[] arr = new int[10];

Indices in C# are zero-based. The indices of the array above will be 0-9. For example:

int[] arr = new int[3] {7,9,4};
Console.WriteLine(arr[0]); //outputs 7
Console.WriteLine(arr[1]); //outputs 9

Which means the system starts counting the element index from 0. Moreover, accesses to
elements of arrays are done in constant time. That means accessing to the first element of the
array has the same cost (in time) of accessing the second element, the third element and so on.

You may also declare a bare reference to an array without instantiating an array.

int[] arr = null; // OK, declares a null reference to an array.
int first = arr[0]; // Throws System.NullReferenceException because there is no actual array.

An array can also be created and initialized with custom values using collection initialization
syntax:

https://riptutorial.com/ 49