c#:构建3D-Array并填充数据

Question

我试过的代码如下:

private static List<List<List<int>>> threeDArrayToThreeDList(int [,,] letters) {
    // 3d-array to 3d-list
    List<List<List<int>>> letterslist = new List<List<List<int>>>();
    List<List<int>> sublist = new List<List<int>> ();
    List<int> subsublist = new List<int> ();
    for (int i = 0; i < 2; i++) {
        letterslist.Add (sublist);
        for (int j = 0; j < 2; j++) {
            letterslist[i].Add (subsublist);
            for (int k = 0; k < 2; k++) {
                Console.WriteLine (letterslist [i][j][k]); // Element not found         
                Console.WriteLine (letters [i,j,k]);
                letterslist [i] [j] [k] = letters [i,j,k];
            }
        }
    }
    return letterslist;
}

为什么没有找到letterslist [i][j][k] ?

Answer 1

你的代码是错误的。您需要为每个"索引"创建一个列表。你的代码总共只创建了3个列表。

它应该是这样工作的:

private static List<List<List<int>>> threeDArrayToThreeDList(int [,,] letters) {
    // 3d-array to 3d-list
    List<List<List<int>>> letterslist = new List<List<List<int>>>();
    for (int i = 0; i < 2; i++) {
        letterslist.Add (new List<List<int>> ());
        for (int j = 0; j < 2; j++) {
            letterslist[i].Add (new List<int> ());
            for (int k = 0; k < 2; k++) {
                Console.WriteLine (letters [i,j,k]);
                letterslist [i] [j].Add(letters [i,j,k]);
            }
        }
    }
    return letterslist;
}

Answer 2

这是因为letterslist [i][j]列表中没有元素。向它添加一个元素，它将带您通过导致异常的行。

将最内层循环中的代码修改如下:

for (int k = 0; k < 2; k++) {
    letterslist[i][j].Add (letters[i, j, k]);
    Console.WriteLine(letterslist[i][j][k]); // Should work fine
    Console.WriteLine(letters[i, j, k]);
}