Use of Array of object instantiation

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I need to instantiate a number of objects related to a particular class. I am using an array to handle this approach -

C#

Task[] task = new Task[4];

and then

C#

for (int i = 0; i <= 3; i++)
{
   task[i] = new Task();
}

However I am not certain if this is the right approach or if there is a more efficient method to handle these different objects.

Thanks

Posted 6-Sep-11 9:37am

tamasu

Updated 6-Sep-11 9:45am

Wendelius

v2

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Wendelius 6-Sep-11 15:45pm

Pre tags added

Philippe Mori 6-Sep-11 19:45pm

As shown in solution 2, if you uses a loop for initialization, it is better to uses the Length property for more maintanable code (avoid cascvading changes if the number of task changes).

2 solutions

Solution 1

If you know how many objects you will have, arrays are great and you will not find anything faster.

If you have an unknown number of objects and need to access them ordered, use List<T> (internally a List uses an array).

There are many other collections, but I must know a little more to explain if any other collection is better than an array or a list for your case.

Posted 6-Sep-11 9:49am

Paulo Zemek

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Wendelius · Accepted Answer · 2011-09-06T09:53:00

Solution 2

That should work fine. Of course there are lot's of alternatives like:
If the amount of tasks is always a constant:

C#

Task[] task = new Task[4]{ new Task(), new Task(), new Task(), new Task() };

If the amount in the declaration can change:

C#

for (int i = 0; i < task.Length; i++)
{
   task[i] = new Task();
}

and so on..

As for storing you can use array which is lightweight and fast but if you want more flexibility and programmability against the collection then you could consider something from System.Collections.Generic Namespace[^]

Posted 6-Sep-11 9:53am

Wendelius

Comments

Philippe Mori 6-Sep-11 19:44pm

If the first form is used, then specifying the size is not required...

Wendelius 7-Sep-11 1:13am

Yes, that's quite true. Personally I prefer to write it since it's easier to to look at the size of an array in definition than to count the number of elements :) Thanks for your comment.

Sergey Alexandrovich Kryukov 7-Sep-11 0:23am

Good point, my 5.
Important to note: OP's use of immediate constants 3 and 4 is a nasty mistake. It will work in this case but impossible to support.
--SA

Wendelius 7-Sep-11 1:14am

Thank you SA

tamasu 8-Sep-11 11:34am

Thanks. My issue is that I need to initially populate the list dynamically, that is the list depends on the user's input. Once the items are defined, they need to be accessed throughout the project.

For instance I have declared an array as: <pre lang="c#">Task[] task = new Task[4]; </pre>. The class Task contains more then one property which are all initially defined by the user. Lets consider that Task 1 was set as "not configured" with its property "status" set as true.

I am not concerned about structuring the get and set but how the same array of objects (in this case 4) is accessed by the other objects and therefore without another instantiation.

Thanks again for your assistance

Wendelius 8-Sep-11 12:13pm

I see. It's a bit different situation than I initially thought. Based on the description I'd use a generic collection, a List perhaps. With a collection you donät have to worry about the amount if items since it's 'self-adjusting' and also you have much better handling capabilities than with an array. For example using LINQ to find items in collection etc. is much more fun than with arrays :)

tamasu 10-Sep-11 16:51pm

Mika thanks for your feedback. If I declare a list in a class this will be made available solely for that class, it will not be available to the other classes. Thanks again.