Question

我想总结两个数字之间的值范围。我提示用户输入2个数字，如果第一个数字更大，那么我想在循环之前将它与第二个数字交换。我怎么能这样做？

import java.util.Scanner;
public class Example {
    public static void main (String []args) {
        Scanner kb = new Scanner(System.in);

        int n1 = 0, n2 = 0, count = 0;

        System.out.print("Enter two limits: ");
        n1 = kb.nextInt();
        n2 = kb.nextInt();

        while ( n1 <= n2 ) {
            count = count + n2;
            n2--;
        }
        System.out.println("The sum from "+ n1 +" to "+ n2 +" is : " + count);
    }
}

我想要的输出告诉我（如果我输入6和10）

the sum from 6 to 10 is 40

但是我的程序输出是

the sum from 6 to 5 is 40

我做错了什么？

Answer 1

可以使用Math.max(int, int)和Math.min(int, int)（以及IntStream，假设您使用的是Java 8+）。像，

Scanner kb = new Scanner(System.in);
System.out.print("Enter two limits: ");
int n1 = kb.nextInt();
int n2 = kb.nextInt();
int start = Math.min(n1, n2), stop = Math.max(n1, n2);
System.out.println("The sum from " + n1 + " to " + n2 + " is : "
        + IntStream.rangeClosed(start, stop).sum());

如果由于某种原因你不能使用Math，或者是一个非常方便的小技巧，你可以做一些你自己的数学;像

int start = n1;
if (n2 < n1) {
    start = n2;
}
int stop = n2 + n1 - start;

或

int start = (n1 < n2) ? n1 : n2, stop = n2 + n1 - start;

Answer 2

Scanner in = new Scanner(System.in);

int n1;
int n2;
int count = 0;

System.out.print("Enter two limits: ");
n1 = in.nextInt();
n2 = in.nextInt();
if (n1 > n2) {
    n1 += n2;
    n2 = n1 - n2;
    n1 -= n2;
}
int current = n1;
while (current <= n2) {
    count += current;
    current++;
}
System.out.println("The sum from " + n1 + " to " + n2 + " is : " + count);

2个数字的范围总和是多少？

2 个答案: