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Retrieving data from a property

Retrieving data from a property

Guest User

14y1.4kC#

Hi

Given the following code I came across:-

ConsoleKeyInfo cki;

cki = Console.ReadKey();

Console.WriteLine("Key pressed: {0}\n", cki.Key);

if (cki.Key == ConsoleKey.X)

break;

My question is, how is the Key property holding the required data without even being set?

The only thing I can see happening is that the instance variable cki is storing the return value captured from the ReadKey method.

Id usually expect to see the something like:-

ConsoleKeyInfo cki = new ConsoleKeyInfo();

cki.Key = Console.ReadKey();

Console.WriteLine("Key pressed: {0}\n", cki.Key);

Regards

Steven

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
This line:

cki = Console.ReadKey();

is creating a ConsoleKeyInfo structure and storing it in the memory slot reserved for the local variable cki on the stack. So cki actually contains the structure rather than a reference to where it's stored elsewhere in memory.

Whilst you're right that structures aren't objects, the terms 'instance' and 'instantiation' can be (and often are) used when creating either of them.
Guest User14y ago
Understood, many thanks Vulpes
Guest User14y ago
And by the line:-

"Is automatically set when the ConsoleKeyInfo structure is instantiated."

Is this referring to

ConsoleKeyInfo cki;

cki = Console.ReadKey();

I thought instantiatation was creating a "new" object?
Vulpes14y ago
The Console.ReadKey() method returns a ConsoleKeyInfo structure which contains details of the key pressed.

In particular it has a read-only Key property which returns a ConsoleKey value. This (or, to be more precise, the underlying field) is automatically set when the ConsoleKeyInfo structure is instantiated.

ConsoleKey is an enumeration which has values for every key on the keyboard. For a list, see here:

http://msdn.microsoft.com/en-us/library/system.consolekey.aspx