Initializing jagged arrays

问题

I want to create array 10 * 10 * 10 in C# like int[][][] (not int[,,]).

I can write code:

int[][][] count = new int[10][][];
for (int i = 0; i < 10; i++) {
    count[i] = new int[10][];
    for (int j = 0; j < 10; j++)
        count[i][j] = new int[10];
}

but I am looking for a more beautiful way for it. May be something like that:

int[][][] count = new int[10][10][10];

回答1:

int[][][] my3DArray = CreateJaggedArray<int[][][]>(1, 2, 3);

using

static T CreateJaggedArray<T>(params int[] lengths)
{
    return (T)InitializeJaggedArray(typeof(T).GetElementType(), 0, lengths);
}

static object InitializeJaggedArray(Type type, int index, int[] lengths)
{
    Array array = Array.CreateInstance(type, lengths[index]);
    Type elementType = type.GetElementType();

    if (elementType != null)
    {
        for (int i = 0; i < lengths[index]; i++)
        {
            array.SetValue(
                InitializeJaggedArray(elementType, index + 1, lengths), i);
        }
    }

    return array;
}

回答2:

You could try this:


int[][][] data =
{
    new[]
    {
        new[] {1,2,3}
    }, 
    new[]
    {
        new[] {1,2,3}
    }
};

Or with no explicit values:


int[][][] data =
{
    new[]
    {
        Enumerable.Range(1, 100).ToArray()
    }, 
    new[]
    {
        Enumerable.Range(2, 100).ToArray()
    }
};

回答3:

There is no built in way to create an array and create all elements in it, so it's not going to be even close to how simple you would want it to be. It's going to be as much work as it really is.

You can make a method for creating an array and all objects in it:

public static T[] CreateArray<T>(int cnt, Func<T> itemCreator) {
  T[] result = new T[cnt];
  for (int i = 0; i < result.Length; i++) {
    result[i] = itemCreator();
  }
  return result;
}

Then you can use that to create a three level jagged array:

int[][][] count = CreateArray<int[][]>(10, () => CreateArray<int[]>(10, () => new int[10]));

回答4:

There is no 'more elegant' way than writing the 2 for-loops. That is why they are called 'jagged', the sizes of each sub-array can vary.

But that leaves the question: why not use the [,,] version?

回答5:

int[][][] count = Array.ConvertAll(new bool[10], x =>
                  Array.ConvertAll(new bool[10], y => new int[10]));

回答6:

A three dimensional array sounds like a good case for creating your own Class. Being object oriented can be beautiful.

回答7:

You could use a dataset with identical datatables. That could behave like a 3D object (xyz = row, column, table)... But you're going to end up with something big no matter what you do; you still have to account for 1000 items.

回答8:

With a little help from Linq

int[][][] count = new int[10][][].Select(t => new int[10][].Select(tt => new int[10]).ToArray()).ToArray();

It sure isn't pretty and probably not fast but it's a one-liner.

回答9:

Why don't you try this?

int[,,] count = new int[10, 10, 10]; // Multi-dimentional array.

Any problem you see with this kind of representation??

来源：https://stackoverflow.com/questions/1738990/initializing-jagged-arrays

标签

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jagged-arrays