如何使用 C# 创建一维、二维、三维以及多维数组？

Question

我试图将 1、2、3、4、5 的所有组合（5C1、5C2、5C3、5C4、5C5）保存到单独的数组中。所以我需要在 c# 中使用 for 循环创建动态数组。

比如说， 这里 n = 5 和 r = 1 到 5。 如果 r = 1 那么 我的数组将是一维数组，当 r = 2 时，它将是二维数组，当 r = 3 时，然后是三维，当 r = 4 时，然后是四维数组，它将一直持续到 5 的末尾。 我的代码如下所示

string[] ShipArrayObj;
  public frmResult( string[] ShipArray )
    {
        InitializeComponent();           
        ShipArrayObj = ShipArray;
    }

    private void frmResult_Load(object sender, EventArgs e)
    {
        string[] arr = ShipArrayObj;           
        int n = ShipArrayObj.Count();
        for (int r = 1; r <= n; r++)
        {                
            StoreCombination(arr, n, r);
            richTextBox1.Text = richTextBox1.Text + "/";                
        }

    }

    void StoreCombination(string[] arr, int n, int r)
    {           
        string[] data = new string[r];            
        createCombination (arr, data, 0, n - 1, 0, r);
    }


   private void createCombination(string[] arr, string[] data, int start, int end, int index, int r)
    {
        if (index == r)
        {
            int j = 0;
            for (j = 0; j < r; j++)
             richTextBox1.Text = richTextBox1.Text + data[j].ToString();//Where I want to set array to keep combination values
             return;
        }

        int i = 0;
        for (i = start; i <= end && end - i + 1 >= r - index; i++)
        {
            data[index] = arr[i];
            CreateCombination(arr, data, i + 1, end, index + 1, r);
        }
    }

我将所有组合存储到富文本框中，但想保留在数组中。如果有人帮助我，我将不胜感激。

Answer 1

如果您习惯于 Java 之类的东西，那么多维数组在 C# 中的语法会有些不同。

Here's a page describing how to do them in C#.这是来自该页面的sn-p：

// Two-dimensional array.
int[,] array2D = new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } };
// The same array with dimensions specified.
int[,] array2Da = new int[4, 2] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } };
// A similar array with string elements.
string[,] array2Db = new string[3, 2] { { "one", "two" }, { "three", "four" },
                                        { "five", "six" } };

// Three-dimensional array.
int[, ,] array3D = new int[,,] { { { 1, 2, 3 }, { 4, 5, 6 } }, 
                                 { { 7, 8, 9 }, { 10, 11, 12 } } };
// The same array with dimensions specified.
int[, ,] array3Da = new int[2, 2, 3] { { { 1, 2, 3 }, { 4, 5, 6 } }, 
                                       { { 7, 8, 9 }, { 10, 11, 12 } } };

If you're interested in different combinations of things with a fixed number of them, something like this should be all you need.

If you're interested in different combinations of things with a dynamic number of them, something like this should be all you need.

（除非你试图优化性能，一般来说，可读性/表达性会更好。）

您可能需要考虑顺序是否重要（无序集与有序列表）。我会假设它不是来自您的代码（在这种情况下，排序可以很好地消除“重复”），但我无法确定。

---

这是一个很好的例子，它易于阅读和修改变化，对于小数字也不错：

// -1, 0, ..., 5
var choices = Enumerable.Range(-1, 6); 

var possibleChoices = 
    from a in choices
    from b in choices
    from c in choices
    from d in choices
    from e in choices
    select (IEnumerable<int>)new [] { a, b, c, d, e };

// Remove -1's because they represent not being in the choice.
possibleChoices =
    possibleChoices.Select(c => c.Where(d => d >= 0));

// Remove choices that have non-unique digits.
possibleChoices =
    possibleChoices.Where(c => c.Distinct().Count() == c.Count());

// Sort the choices to indicate order doesn't matter
possibleChoices =
    possibleChoices.Select(c => c.OrderBy(d => d));

// Remove duplicates
possibleChoices = 
    possibleChoices.Select(c => new 
                           {
                               Key = string.Join(",", c),
                               Choice = c
                           }).
    GroupBy(c => c.Key).
    Select(g => g.FirstOrDefault().Choice);

foreach (var choice in possibleChoices) {
    Console.Out.WriteLine(string.Join(", ", choice));
}

输出：

0
1
2
3
4
0, 1
0, 2
0, 3
0, 4
1, 2
1, 3
1, 4
2, 3
2, 4
3, 4
0, 1, 2
0, 1, 3
0, 1, 4
0, 2, 3
0, 2, 4
0, 3, 4
1, 2, 3
1, 2, 4
1, 3, 4
2, 3, 4
0, 1, 2, 3
0, 1, 2, 4
0, 1, 3, 4
0, 2, 3, 4
1, 2, 3, 4
0, 1, 2, 3, 4

---

这可能更容易理解，硬编码到这种特定的组合变体并涉及递归，但更通用/没有硬编码为5（并在dotnetfiddle上采用0.047s .net 而不是 0.094s)。也完全是懒惰的/IEnumerable。

public static void Main()
{       
    var possibleChoices = Choose(5);

    foreach (var choice in possibleChoices) {
        Console.Out.WriteLine(string.Join(", ", choice));
    }
}

public static IEnumerable<IEnumerable<int>> Choose(int max) 
{       
    var remaining = Enumerable.Range(0, max); 

    return ChooseRecursive(remaining, Enumerable.Empty<int>());
}

public static IEnumerable<IEnumerable<int>> ChooseRecursive(IEnumerable<int> remaining, IEnumerable<int> chosen) 
{       
    yield return chosen;

    foreach (var digit in remaining) 
    {
        var choices = ChooseRecursive(
            remaining.Where(d => d > digit), 
            chosen.Concat(new [] { digit })
        );
        foreach (var choice in choices)
        {                   
            yield return choice;
        }
    }
}

输出：

0
0, 1
0, 1, 2
0, 1, 2, 3
0, 1, 2, 3, 4
0, 1, 2, 4
0, 1, 3
0, 1, 3, 4
0, 1, 4
0, 2
0, 2, 3
0, 2, 3, 4
0, 2, 4
0, 3
0, 3, 4
0, 4
1
1, 2
1, 2, 3
1, 2, 3, 4
1, 2, 4
1, 3
1, 3, 4
1, 4
2
2, 3
2, 3, 4
2, 4
3
3, 4
4