Javascript中的2D数组 [英] 2D Arrays in Javascript

问题描述

对于大学来说，关于2D数组，我们有一个问题需要解决，但是它们的本质从未在课堂上介绍过.我已经在这个网站上搜寻了答案(这可能在我的代码中很明显)，但无法使其正常工作，甚至无法真正理解正在发生的事情或原因.确切的问题是:

For college, we have a problem to solve regarding 2D arrays, however the nature of them has never been cover in class. I've scoured this site for answers(which might be evident in my code) but cannot get it to work, or even truly understand what is going on or why. The exact question is:

Write a program that utilises a 8x8 2-dimensional array.  
(a) Initialise the array elements via nested for loops as follows

1  2  3  4  5  6  7  8
9  10 11 12 13 14 15 16
17 18 19 20 21 22 23 24
25 26 27 28 29 30 31 32
...
...
57 58 59 60 61 62 63 64

(b) Add some code that will display all array elements in an 8x8 HTML table.

(c) Use nested for loops for calculating the sum and the average of the
    values stored in the array.
    Let a function display these values on screen eg use alert().   

---

到目前为止，我的代码是:

x = matrix( 8 , 8, 0 ); // 8 lines, 8 cols filled with empty string

function matrix( rows, cols, defaultValue){

   var arr = [];

     // Creates all lines:
     for(var i=0; i < rows; i++){

     var add = 1 

    // Creates an empty line
     arr.push([]);

      // Adds cols to the empty line:
     arr[i].push( new Array(cols));

        for(var j=0; j < cols; j++){
        // Initializes:
            arr[i][j] = defaultValue + add;
         }
  var add = add + 1
 }
    return arr;
}

function displayInDiv() {
  var output_string_ = "" ;
  var lastElement = 64 ;


output_string_ = output_string_
                +'<table>'
                +'<tr>'
                +'<th width="11%" align="left">ARRAY INDEX</th>'
                +'<th width="11%" align="right"> array_1</th>'
                +'<th width="11%" align="right"> array_2</th>'
                +'<th width="11%" align="right"> array_3</th>'
                +'<th width="11%" align="right"> array_4</th>'
                +'<th width="11%" align="right"> array_5</th>'
                +'<th width="11%" align="right"> array_6</th>'
                +'<th width="11%" align="right"> array_7</th>'
                +'<th width="11%" align="right"> array_8</th>'
                +'</tr>'
                ;

for ( var i = 1 ; i < 9 ; i++ ) { 

    for ( var j = 0 ; j < 7 ; j++ ) {

    output_string_ = output_string_
                    +'<tr id="table_row_'
                    + i
                    +'">'
                    +'<td width="11%" align="left">'
                    +'['
                    + i
                    +']'
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'<td width="11%" align="right">'
                    + Array[i][j]
                    +'</td>'
                    +'</tr>'
                    ;
}

    output_string_ = output_string_
                +'<table>'
                ;


var output_section_ = document.getElementById("list_");
output_section_.innerHTML = output_string_ ; 

}
}

---

抱歉，文本转储很大，但我完全被困住了.任何帮助将不胜感激.

---

Sorry for the huge text dump, but i'm completely stumped. Any help would be greatly appreciated.

推荐答案

我相信您要查找的确切代码是

I believe the exact code you're looking for is this

var outer = new Array();

for(var i = 0; i < 8; i++) {
  var inner = new Array
  for(var j = 0; j < 8; j++) {
    inner[j] = (i * 8) + j + 1;
  }
  outer[i] = inner;
}

console.log(outer);

2D数组只是数组的数组，在这里我将它们标记为内部和外部.

A 2D array is just an array of arrays, here I labelled them inner and outer.

有8个长度为8的内部数组，总共有64个条目.每个条目的值都是8 *外部索引(从0开始)，加上内部索引加1(因为它也从0开始).

There are 8 inner arrays of length 8, giving you 64 total entries. The value of each entry is 8 * the outer index (which starts at 0), plus the inner index plus 1 (because it also starts at 0).

这应该为您提供足够的信息，以便您自己回答部分 b 和 c ，但是如果您需要进一步的帮助，请在下面发表评论.:)

This should give you enough information to answer parts b and c yourself, but feel free to comment below if you'd like further help. :)

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