C# struct array assignment

Question

4.00/5 (1 vote)

See more:

Hi,

I have defined a struct in C#. Inside this struct I have an array of integers. This field is ImagesLoadStatus as below.

C#

struct ProductImages
   {
       public string ImageB;
       public string ImageS;
       public string ImageOrg;
       public int[] ImagesLoadStatus;

  }

In another class I am initializing the array. Here:

C#

ProductImages prdImages = new ProductImages();
for (int i = 0; i < 4; i++)
    prdImages.ImagesLoadStatus[i] = 0;

I build the application without error. But a warning message appears saying :

warning CS0649: Field 'ProjectName.ClassFolder.ProductImages.ImagesLoadStatus' is never assigned to, and will always have its default value null

I am already initializing he array in the struct, why do I get such a warning message ?

Thanks in advance,

Posted 27-Jan-11 4:12am

Close Network

Updated 27-Jan-11 4:13am

OriginalGriff

v2

Add a Solution

Comments

OriginalGriff 27-Jan-11 10:29am

Please note, Nish and I have both been corrected by SAKryukov - you shouldn't use literal constants as loop guards. We didn't spot that - sorry!

3 solutions

Solution 3

Your initial code or your constructor should really create this array and set default values, the code as it stands is quite fragile and requires all users to check for null, etc.

Posted 27-Jan-11 4:31am

Christian Graus

Comments

Close Network 27-Jan-11 14:20pm

I am sorry. I didn't quite understand your point ? Could you clarify a little bit by adding some code ? Thanks,

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Nish Nishant · Accepted Answer · 2011-01-27T04:12:00

Solution 1

The array itself is never initialized. You need to do that too.

Example:

C#

ProductImages prdImages = new ProductImages();
prdImages.ImagesLoadStatus = new int[ProductImages.MAXBUFFER];
int initValue = 7; // arbitrary example
int minCount = 5; // arbitrary example
for (int i = 0; i < Math.Min(minCount, prdImages.ImagesLoadStatus.Length); i++)
    prdImages.ImagesLoadStatus[i] = initValue;

Posted 27-Jan-11 4:12am

Nish Nishant

Updated 28-Jan-11 3:39am

v5

Comments

Close Network 27-Jan-11 10:13am

Î am already doing that. Here:
for (int i = 0; i < 4; i++)
prdImages.ImagesLoadStatus[i] = 0;

Nish Nishant 27-Jan-11 10:15am

No, you are not. That only sets the array members, not the array itself. Check my updated answer and look at the highlighted line of code.

Close Network 27-Jan-11 10:16am

OK, thanks a lot.

Nish Nishant 27-Jan-11 10:16am

You are welcome.

Sergey Alexandrovich Kryukov 27-Jan-11 10:25am

Nishant, not 4, replace with array size. Using 4 here would be a plain bug.
Thank you.
--SA

Nish Nishant 27-Jan-11 10:26am

I actually used 20 to be safe, but I reckon in his actual code he'd have a const int or something that he'd use.

Nish Nishant 27-Jan-11 10:27am

Ah you meant the for-loop, yeah I see what you mean :-)

OriginalGriff 27-Jan-11 10:28am

Yep, I made the same whoopsie, too!

Nish Nishant 27-Jan-11 10:29am

:-)

Nish Nishant 27-Jan-11 10:28am

Updated my answer, thanks.

Sergey Alexandrovich Kryukov 27-Jan-11 21:28pm

Nishant, why are yout still showing a code with 4? I see no point...

Nish Nishant 27-Jan-11 21:36pm

Updated the code. It now uses Math.Min (since he specifically wants 4 items irrespective of the array length). Thank you.

Sergey Alexandrovich Kryukov 27-Jan-11 22:10pm

Again, it misses the purpose. Why 20 then? Instead, OP could be noted about bad design.
Don't you think so?
--SA

Nish Nishant 28-Jan-11 9:39am

You are a tough guy to please, Kryukov :-)

Anyway, I have updated my answer, so it should be quite better now. Thank you.

Sergey Alexandrovich Kryukov 28-Jan-11 11:58am

Pleasing me is not your responsibility :-) I'm surprised you take it so seriously.
Thank anyway and best wishes!
--SA

Nish Nishant 28-Jan-11 11:59am

Well both you and me, we share a common aim to give the OP the best answer possible. So I actually enjoy the criticism I get from you :-)

Sergey Alexandrovich Kryukov 28-Jan-11 13:54pm

I can feel it. My pleasure. Good to talk with you.

Can I also say I am personally very much driven by criticism.
I think at school and especially at university (which is famous PhysTech) we had a very harsh but I think very productive cultural background. Should you ever dare to say that you became and expert in any topic, one of your best friends will take if for great honor to challenge you with some more difficult problem in order to dip your face in dirt and say: "you still think you really understand the matter well?". If your find it offensive nobody will respect you. People around will only respect you if you meet a challenge properly; they will respect you even more if your have enough bravery to say "I failed; now I understand it". Can you see why this is very productive? Very often you can learn from fellow students more then from professors (especially taking into account one of my course mates won a Nobel prize in 2010 and some part of other students around had decent skills).

Unfortunately, in US this presents some cultural barrier. Most of co-workers are educated by hearing "Good job!" in almost all cases and did not learn how to work on criticism to improve instead of protecting themselves. I see you work in US, too, so you should know that...

--SA

OriginalGriff · Accepted Answer · 2011-01-27T04:15:00

Solution 2

When you use the array, you are assigning values to the individual elements.

prdImages.ImagesLoadStatus[i] = 0;

However, you do not assign the actual array. Add the one line:

C#

ProductImages prdImages = new ProductImages();
prdImages.ImagesLoadStatus = new int[myArraySize];   // Add this line.
for (int i = 0; i < prdImages.ImagesLoadStatus.Length; i++)
    prdImages.ImagesLoadStatus[i] = 0;

And it should be fine.

[edit]Changed loop guard to array size - OriginalGriff[/edit]

Posted 27-Jan-11 4:15am

OriginalGriff

Updated 27-Jan-11 4:27am

v2

Comments

Close Network 27-Jan-11 10:19am

I have already added, thanks..

Sergey Alexandrovich Kryukov 27-Jan-11 10:24am

Griff, not 4, replace with myAttaySize. Using 4 here would be a plain bug.
Thank you.
--SA

OriginalGriff 27-Jan-11 10:27am

Good point - changed to use array size.

Sergey Alexandrovich Kryukov 27-Jan-11 21:27pm

My vote of 5. Thank you.
--SA

unolegg 14-Sep-15 0:50am

Coming from C background, it takes time getting used with the c# convention. Your example is concise and clear - Thank you!