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Working with List in Structure c#

Posted on 2009-05-10
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Last Modified: 2012-05-08
Hello,

I have 2 structures, (example) 1 called Woords and the other one called Sentence.
Sentence contains nothing more then a List<> of Woords.

Now when I try to add Woords to the List on Sentence it says "NullReferenceException". Now I can understand that I need to create a New List before adding any items to it, but can't figure out how to do it with the structs.
See sample code below:

thx


// my structs
public struct structWoords
       {
           public string woord1;
           public string woord2;
       }
 
       public struct structSentence
       {
         public List<structWoords> woords ; 
       }
 
//code
Structs.structWoords myWords;
            myTest.woord1 = textBox1.Text;
            myTest.woord2 = textBox2.Text;
 
            Structs.structSentence mySentence = new Structs.structSentence();
            mySentence.woords.Add(myWords); // error happens here
 
//  I think the problem is that I don't make a new List but don't know how to do it with the struct...

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Question by:Pit76
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Expert Comment

by:zwei
ID: 24349811
You can't initialize variables in a struct, as far as I know.  You'll have to do it outside the struct:


mySentence.woords = new List<string>();

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Accepted Solution

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zwei earned 500 total points
ID: 24349819
oops I meant
new List<structWoords>();

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Author Comment

by:Pit76
ID: 24350044
where do i need to put that line of code then?
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Author Closing Comment

by:Pit76
ID: 31656982
Thx, I found where to put that line of code.. :)

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LVL 6

Expert Comment

by:Cebik
ID: 24350106

public struct structSentence
{
    public List<structWoords> woords; //cannot have instance field initializers in structs
}
 
public class structSentence2
{
    public List<structWoords> woords = new List<structWoords>();
}
 
//Code
structSentence mystruct = new structSentence();
mystruct.woords = new List<structWoords>();
(..)
 
//or
structSentence2 mystruct2 = new structSentence2();

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