C# - float[][] declaration

Question

I'm trying to declare this kind of variable:

float[][]

Things that didn't work for me (wouldn't compile) -

float[][] inputs = new float[10][5];
float[][] inputs = new float[10,5];

When trying to declare the array like this -

int a = 3;
int b = 2;
float[][] inputs = new float[][]
{
   new float[a],
   new float[b]
};

I get a multidimensional array with two float arrays instead of an array that has 3 arrays and every array size is 2.

Answer 1

嗯，有两种不同的类型：

• 数组数组（锯齿状数组）：

  float[][] sample = new float[][] {
    new float[] {1, 2, 3},
    new float[] {4, 5}, // notice that lines are not necessary of the same length
  };
  

• 二维数组：

  float[,] sample2 = new float[,] {
    {1, 2, 3},
    {4, 5, 6},
  };
  

编辑：您的代码修改：

  // jagged array (10 arrays each of which has 5 items)
  float[][] inputs = new float[10][] {
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
    new float[5],
  };

您可以在Linq的帮助下缩短声明：

  float[][] inputs = Enumerable
    .Range(0, 10)               // 10 items
    .Select(i => new float[5])  // each of which is 5 items array of float
    .ToArray();                 // materialized as array

或者在二维数组的情况下

  // 2d array 10x5
  float[,] inputs = new float[10,5];