reference type issue ?

SUNIL GUTTA

13y1.4kVisual Basic .NET

Hi friends

well i got some dam silly doubt may be here it is

Well array is a reference type right of array have n elements then its length will be "n" via array.length property

But when array has nothing in it like say length is "ZERO" i we try to find out :)

As array is a reference type it stores default "NULL" i.e value types "ZERO" as known ..

So,wen there are no elements present in it HOW COME LENGTH BECOME "ZERO" is there any conversion going on :)

How come we decide a length of a nothing present :-p

Thank you

3 Replies

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Vulpes13y ago
Accepted answer
Yes, the length of an empty array is zero.

When you create an array you usually specify the length within the []. So:

int[] arr = new int[0];

creates an empty array object and assigns a reference to it to the variable 'arr'.

'Empty' simply means that the array doesn't contain any elements at all. It doesn't mean that it contains a single element whose value is zero or null. The latter would be dealt with as follows (using the most verbose syntax):

int[] arr = new int[1]{0};
object[] arr = new object[1]{null};

Notice that an int array can't contain the value null because int is a value type. However, an object array can contain such a value because object is a reference type.
SUNIL GUTTA13y ago
Just perfectly constructed explanation TY for it but small doubts

lbeit an empty one
finally u mean to say size of an empty array is ZERO right :)

But u said arr[0] which doesn't contain anything just empty ..

IS empty means ZERO or NuLL or anything ?
Vulpes13y ago
As you say an array is a reference type whose length remains fixed once it has been created.

Methods which appear to change the length such as Array.Resize() do in fact create a new array to which the original elements are copied.

So, if an array is to have a zero length, then it must be created with a zero length to start with:

int[] empty = new int[0];

Even though it has no elements, an empty array is nevertheless a valid array object.

Note though that an empty array is not the same thing as a null array reference.

int[] ia = null;

All this means is that the integer array variable, ia, doesn't currently refer to an array object.

If you then do this:

ia = new int[0];

it does now refer to an array object, albeit an empty one.