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  • 数组 2017-03-19

    一、三种定义方式:

    (1)       var arr=Array(x);  ----大写

    arr[k]=”a”;

    注:x为数组长度,弱类型语言中一般不写; k为索引值,0开始计数;a为value。

    (2)       var attr=[“a”,”b”];

    (3)       var attr=Array(“a”,”b”); 或者var attr= new Array(“a”,”b”);  一般不加new.

    Var x=attr.length;  表示数组长度。

    arr.push(“d”); 将加入数组arr中。

    常用第一种和第二种;注意书写方式

    二、遍历数组

     第一种:

    for(var i=0;i<attr3.length;i++){

                                                     alert(attr3[i]);

                                              }

    第二种:

    for(var k in arr){

                                                     alert(k + "-------" +arr[k]);

                                              }

       注: k为名字,不是索引值,但等同于索引值,0开始

            arr(k)是数组的值。

    三、例题

    1、求一个数组中的最大值、最小值和总和。

    <script>

                var attr=Array();

                for(var i=0; i<5; i++){

                       var arr= prompt("请输入第"+(i+1)+"个数据");

                       attr.push(arr);

                }

                for(var x in attr){

                       alert(attr[x]);

                }

                var sum=0;

                var max=attr[0];

                var min=attr[0];

                for(var x in attr){

                       sum+=parseInt(attr[x]);

                       if (attr[x]>max){

                              max=attr[x];

                       }

                       if (attr[x]<min){

                              min=attr[x];

                       }

                }

                alert(min+"+"+max+"+"+sum);

                </script>

    2、输入去重

    var attr = Array();

                                            for(var i = 0; i < 5; i++) {

                                                   var x = prompt("请输入第" + (i + 1) + "个数据")

                                                   var status = false;

                                                  

                                                   for(var y in attr){

                                                          if(attr[y] == x)

                                                          {

                                                                 status = true;

                                                          }

                                                   }

                                                   if(status == true)

                                                   {

                                                          continue;

                                                   }

                                                   attr.push(x);

                                            }

                                           

                                            for(var z in attr)

                                            {

                                                   alert(attr[z]);

                                            }

    难点:设置初始值。

    3、冒泡排序法(重点)

         var attr = Array();

                       for(var i = 0; i < 5; i++) {

                              attr[i] = parseInt(prompt("请输入第" + (i + 1) + "个数字"));

                       }

                       for(var x = 0; x < 5; x++) {

                              for(var y = x + 1; y < 5; y++) {

                                     if(attr[x] < attr[y]) {

                                            var temp = attr[x];

                                            attr[x] = attr[y];

                                            attr[y] = temp;

                                     }

                              }

                       }

                       for(var k in attr)

                       {

                              alert(attr[k]);

                       }

    难点:数据交换:

    var a = 1;

                                            var b = 2;

                                            var temp;

                                            temp = a;

                                            a = b;

                                            b = temp;

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  • 原文地址:https://www.cnblogs.com/chenguanai/p/6579385.html
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