Java编程: How do I make this for loop program that accepts user input subtract the input properly?

Question

我正在制作一个程序，接受用户输入以减去用户所需的所有数字

我首先让程序询问用户要减去多少个数字，并在 int inputNum 中初始化值，然后将其传递给 for 循环 for (int Count= 1; Count<=inputNum; Count++)，让程序根据inputNum 循环获取用户输入。

不幸的是，输出是错误的。我不明白这将如何正常工作。

我尝试通过将 difference =- toBeSubtracted; 转换为 difference -= toBeSubtracted; 来切换 difference 中的运算符。

对于difference =- toBeSubtracted;，这是一个示例输出

run:
How many numbers do you want to subtract? 
2
Input numbers you want to subtract: 
10
5
The difference of those numbers is -5

对于difference -= toBeSubtracted;，这是一个示例输出

run:
How many numbers do you want to subtract? 
2
Input numbers you want to subtract: 
10
5
The difference of those numbers is -15

代码如下:

import java.util.*;
public class ForLoops_Difference 
{
    public static void main(String[] args) 
    {
        Scanner scan = new Scanner (System.in);
        System.out.println("How many numbers do you want to subtract? ");
        int inputNum = scan.nextInt();
        int difference = 0;

        System.out.println("Input numbers you want to subtract: ");
        for (int Count = 1 ;Count<=inputNum; Count++)
        {
            int toBeSubtracted = scan.nextInt();
            difference =- toBeSubtracted;
        }
        System.out.println("The difference of those numbers is " + difference);
    } 
}

Answer 1

好的，这可能对你有帮助:

difference = 0

比你有:

difference -= toBesubtracted

所以你正在做的是:

difference = difference - toBeSubtracted

换言之

difference = 0 - 10
difference = -10 - 5

因此你得到-15

你在哪里

difference =- toBeSubtracted

和

一样

difference = -1 * toBeSubtracted

因此你得到-5

我想你想要 5 的输出。这是你的代码，只做了一处更改

import java.util.*;
public class ForLoops_Difference 
{
    public static void main(String[] args) 
    {
        Scanner scan = new Scanner (System.in);
        System.out.println("How many numbers do you want to subtract? ");
        int inputNum = scan.nextInt();
        int difference = scan.nextInt(); // so read in the first number here.

        System.out.println("Input numbers you want to subtract: ");
        for (int Count = 1;Count<inputNum; Count++) // go till from 1 to inputNum - 1 because you have already got one number above
        {
            int toBeSubtracted = scan.nextInt();
            difference -= toBeSubtracted;
        }
        System.out.println("The difference of those numbers is " + difference);
    } 
}