Question

我正在尝试创建一个程序，该程序查找某人输入的一组数据的平均值。我尝试使用此代码：

var data = [];
var yesno = confirm("Would you like to add more data?");
while (yesno) {
  var newdata = +prompt("Enter a piece of data (must be a number)");
  data.push(newdata);
  var yesno = confirm("Would you like to add more data?");
}
var total = 0;
var i = 0;
if (!yesno) {
  while (i < data.length) {
    total + data[i];
    i++;
  }
  var average = total / data.length;
  document.write(average);
}

但是，当我运行它时，无论我插入什么内容，它都始终显示“ 0”。预先感谢您的帮助。

Answer 1

问题出在行

total + data[i];

此代码将在某些结果执行后生成。但是，那值什么都没有发生。在javascript中，数字是原始类型。除对象外，所有数据类型对象。您无法使用=对它们进行突变（将它们分配为一个值）。

您需要使用赋值表达式。

total = total + data[i];

否则将是

total += data[i];

另一个问题是您没有将prompt()的结果转换为Number。使用Unary Plus +将字符串转换为数字。

下面是代码的正确版本。

var data = [];
var yesno = confirm("Would you like to add more data?");
while (yesno) {
  var newdata = +prompt("Enter a piece of data (must be a number)");
  data.push(newdata);
  var yesno = confirm("Would you like to add more data?");
}
var total = 0;
var i = 0;
if (!yesno) {
  while (i < data.length) {
    total += data[i];
    i++;
  }
  var average = total / data.length;
  document.write(average);
}

使用do-while和reduce()

可以获得更好，更好的版本

var data = [];
var yesno;
do{
  var newdata = +prompt("Enter a piece of data (must be a number)");
  yesno = confirm("Would you like to add more data?");
  data.push(newdata);
}
while (yesno);
var total = data.reduce((ac,a) => ac + a,0);
var average = total / data.length;
document.write(average);

Answer 2

total + data[i]是一个“孤立的表达式”。使用=或+=。

var data = [];
var yesno = confirm("Would you like to add more data?");
while (yesno) {
  var newdata = +prompt("Enter a piece of data (must be a number)");
  data.push(newdata);
  var yesno = confirm("Would you like to add more data?");
}
var total = 0;
var i = 0;
if (!yesno) {
  while (i < data.length) {
    total += data[i];
    i++;
  }
  var average = total / data.length;
  document.write(average);
}

Answer 3

尝试一下：

var data = [];
var yesno = confirm("Would you like to add more data?");
while (yesno) {
    var newdata = prompt("Enter a piece of data (must be a 
    number)");
    data.push(newdata);
    var yesno = confirm("Would you like to add more 
    data?");
}
var total = 0;
var i = 0;
if (!yesno) {
    while (i < data.length) {
        total += data[i];
        i ++;
        var average = total / data.length;
document.write(average);
        } 
    }

平均取景器始终打印“ 0”

3 个答案: