对于foreach循环中的每个循环？

This gives error. Any other method to extract elements from a multi dimensional array one by one ?

这给出了错误。从一个多维数组中逐个提取元素的任何其他方法?

I thought that for a foreach loop(variable holding corresponding value : array/Iterable), it is possible to first get the one dimensional array from a multiD. array and then create another foreach loop that extract elements from that array. But it gives all sorts of errors in foreach loop.

我认为对于foreach循环(变量持有相应的值:array / Iterable),可以首先从multiD获取一维数组。然后创建另一个foreach循环,从该数组中提取元素。但它在foreach循环中给出了各种错误。

1st error: Array2D.java:14: error: not a statement for(a : arr[] )

第一个错误:Array2D.java:14:错误:不是(a:arr [])的声明

Code Behind:

class Array2D {
    public static void main(String[] args) {
        int[][] array = new int[][]
        {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 }
        };

        int a[] = new int[3];

        for(a : array) {
            for(int n : a) {
                System.out.print(n + " ");
            }
        }
    }
}

4 个解决方案

#1

You need to change the first for statement. Also, you must move the int[] a declaration:

您需要更改第一个for语句。此外,您必须移动int []一个声明:

for(int[] a : arr) {
    ...
}

#2

C# supports the following arrays:

C#支持以下数组:

single-dimensional arrays
multidimensional arrays (also called rectangular arrays)

多维数组(也称为矩形数组)

array-of-arrays (also called jagged arrays).

数组数组(也称为锯齿状数组)。

Examples:

int[] numbers; // Single-dimensional arrays // 1

string[,] names; // Multidimensional arrays // 2

int[][] detail;  // jagged arrays // 3

It is worthy to note that in C# arrays are objects and must be instantiated.

值得注意的是,C#数组是对象,必须实例化。

So, instantiation for the above samples might look like:

因此,上述示例的实例化可能如下所示:

int[] numbers = new int[5];  // 1

string[,] names = new string[5,4]; // 2

int[][] detail = new int[7][];    // 3
for (int d = 0; d < detail.Length; d++)
{
  detail[d] = new int[10];
}

As to your sample, it might be rewritten to the following way:

对于您的示例,可能会按以下方式重写:

static void Main(string[] args)
{
    int[][] arr = new int [][]
    {
        new int[] {1,2,3},
        new int[] {4,5,6},
        new int[] {7,8,9}
    };

    for (int i = 0; i < arr.Length; i++)
    {
        for (int j = 0; j < arr[i].Length; j++)
        {
            System.Console.Write(arr[i][j] + " ");
        }
        System.Console.WriteLine();
    }
}

With Java, I think it will look like

使用Java,我认为它看起来像

for(int[] arr : array)
{
    for(int n : arr)
    {
        System.out.print(n + " ");
    }
}

#3

I would try:

我会尝试:

for (int r = 0; r < arr.length; r++) {
   for (int c = 0; c < arr[r].length; c++) {
      // c and r are the indexes into the array
   }
}

which gives you the indexes of the array element by iterating across the length of each array/array row.

它通过遍历每个数组/数组行的长度为您提供数组元素的索引。

Or if you just need the elements without the indexes

或者,如果您只需要没有索引的元素

   for (int[] a : arr) {
      for (int b : a) {
         // gives you the element in b
      }
   }

#4

-1

In the first for put:

在第一次投入:

for(a : arr) {
//
}

#1