如何创建所有数字组合的n维数组？

我想创建一个函数AllCombnations(d, maxValue)这将创建一个包含从 0 到 的所有数字组合的 d 维数组maxValue.

例如，在 3D 空间中创建所有数字组合（从 0 到maxValue可能是这样的：

for (int i = 0; i < maxValue; i++)
    for (int j = 0; j < maxValue; j++)
        for (int k = 0; k < maxValue; k++)
        {
            // code here
        }

我面临的问题是我不能嵌套 nfor 循环，我不确定我会如何处理这个问题。我考虑过递归，但没有成功。任何帮助将不胜感激。

其实，你can循环维度。请看一下Array https://learn.microsoft.com/en-us/dotnet/api/system.array?view=netframework-4.7.2 class

Demo:

                    // [6, 6, 6] array
int rank = 3;       // 3D array - 3 dimensions
int maxValue = 6;   // Each dimension is of size 6

int[] lengths = Enumerable // {6, 6, 6} - lengths of the dimensions:
  .Repeat(maxValue, rank)  // rank times maxValue 
  .ToArray();              // materialized as array

//TODO: put the right type of arrays' items 
// In demo, let array be of type string: "string[6, 6, 6] array"
var array = Array.CreateInstance(typeof(string), lengths);

// we can't use hardcoded set (i, j, k) of variables 
// we have to address array's item via array of rank length
int[] address = new int[array.Rank];

// Single loop over all array's items (and dimensions)
do {
  //TODO: put the right value here by given address:
  //      (i == address[0], j == address[1], k == address[2] etc.)
  array.SetValue(
    string.Concat(address.Select(i => (char) (i + 'A'))), // value: "AAA", "AAB" etc. 
    address);                                             // address: [0,0,0], [0,0,1], 

  // here we compute next address
  for (int i = 0; i < address.Length; ++i)
    if (address[i] >= array.GetLength(i) - 1)
      address[i] = 0;
    else {
      address[i] += 1;
      break;
    }

  // if we get {0, 0, ..., 0} address, we've exhausted all the items
}
while (!address.All(index => index == 0));

让我们看一下数组（20顶级项目）：

  Console.WriteLine(string.Join(Environment.NewLine, array.OfType<string>().Take(20)));

Outcome:

AAA
AAB
AAC
AAD
AAE
AAF
ABA
ABB
ABC
ABD
ABE
ABF
ACA
ACB
ACC
ACD
ACE
ACF
ADA
ADB