Create c# object array of undefined length?

Question

I would like to create an object array in C# of undefined length and then populate the array in a loop like so...

    string[] splitWords = message.Split(new Char[] { ' ' });

    Word[] words = new Word[];
    int wordcount = 0;
    foreach (string word in splitWords)
    {
        if (word == "") continue;
        words[wordcount] = new Word(word);
        wordcount++;
    }

However, I get the error... "Array creation must have array size or array initializer"

I'm doing a lot more logic in the foreach loop that I've left out for brevity.

Answer 1

What you want to do is create:

List<Word> words = new List<Word>();

and then:

words.Add(new Word(word));

And finally when the loop is done if you need an array:

words.ToArray();

Answer 2

You can't create an array of undefined length. This is where you'd use a generic List.

List<Word> words = new List<Word>();

Answer 3

If you're using C# 3.5, you can just do the following.

var words = message
  .Split(new char[]{' '}) 
  .Where(x => x != "")
  .Select(x => new Word(x))
  .ToArray();

Answer 4

I solved it by using an ArrayList and then casting it to the object array after iterating...

    string[] splitWords = message.Split(new Char[] {' '});
    ArrayList wordList = new ArrayList();
    int wordcount = 0;
    foreach (string word in splitWords)
{
        if (word == "") continue;
        Word newWord = new Word(word);
        wordList.Add(newWord);
        wordcount++;
}
    Word[] words = (Word[])wordList.ToArray(typeof(Word));

I've heard the whole "create question/answer just to document it for others" is acceptable. Plus I'd like to hear if there are better suggestions. Thanks.

Answer 5

Actually you may use list to populate your words first and then convert it easily to array like this:

string[] splitWords = message.Split(new Char[] { ' ' });

List<Word> words = new List<Word>();
int wordcount = 0;
foreach (string word in splitWords)
{
    if (word == "") continue;
    words.add(new Word(word));
    //wordcount++;
}

wordcount = words.count;
return words.ToArray();

Answer 6

A friendly note, you can pass option to split to ignore empty entries. Assuming no other logic to prune out entries you can preinitialize your array like so:

string[] splitWords = message.Split(new Char[] {' '},
  StringSplitOptions.RemoveEmptyEntries);
Word[] words = new Word[splitWords.Length];