Java函数未返回预期值

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英文:

Java function is not returning expected value

问题

程序中的一个错误。我正在为我的Java作业编写此程序。

目标: 该程序应该接受两个参数,并找到这些参数之间的所有奇数,然后返回所有这些数字的总和。

错误: 当参数为负数或起始数字大于结束数字时,应返回-1。但是我的程序返回0。

也许我的程序没有在循环内更新总和值。但是即使如此,根据返回条件,我的函数应该返回-1,而不是总和。

public class SumOddRange{
    public static void main(String[] args){
        System.out.println(sumOdd(10,5));
    }
    
    public static boolean isOdd(int number){
        return (number < 0) || (number % 2 == 0) ? false : true;
    }
    
    public static int sumOdd(int start, int end){

        int sum = 0;
        for(int i = start; i <= end; i++){
            if(isOdd(i)){
                sum += i;
            }
        }
        return (start <= 0) && (start > end) ? -1 : sum;
    }
}
英文:

A bug in a program I'm writing as an assignment for my java.
Objective: program should take two parameters and find all the odd numbers between those parameters. Then it should return the sum of all those numbers.

Bug: When the parameters are negative or starting number is greater than the ending number, it should return -1. But my program is returning 0.

Maybe my program isn't updating the sum value inside the loop. But even so, as per return condition, my function should return -1, not the sum.

public class SumOddRange{
	public static void main(String[] args){
		System.out.println(sumOdd(10,5));
	}
	
	public static boolean isOdd(int number){
		return (number&lt;0)||(number%2==0)?false:true;
	}
	
	public static int sumOdd(int start, int end){

		int sum = 0;
		for(int i=start; i&lt;=end; i++){
			if(isOdd(i)){
				sum+=i;
			}
		}
		return (start&lt;=0)&amp;&amp;(start&gt;end)? -1: sum;
	}
}

答案1

得分: 3

把输入检查放在方法的第一部分,并将 && 改为 ||,因为你希望在第一个检查失败时返回,或者在第二个检查失败时返回,不仅仅是在两者都失败时返回。isOdd 可以内联:

public static int sumOdd(int start, int end){
    if (start <= 0 || start > end)
        return -1;

    int sum = 0;
    for (int i = start; i <= end; i++) {
        if (i % 2 != 0) { // 或者 if (i % 2 == 1) {
            sum += i;
        }
    }
    return sum;
}
英文:

Put the input check as the first thing in your method and change the &amp;&amp; to an || since you want to return if the first check fails or the second check fails, not only if both fail. And the isOdd can be inlined:

public static int sumOdd(int start, int end){
    if (start &lt;= 0 || start &gt; end)
        return -1;

    int sum = 0;
    for (int i = start; i &lt;= end; i++) {
        if (i % 2 != 0) { // or if (i % 2 == 1) {
            sum += i;
        }
    }
    return sum;
}

答案2

得分: 1

在您的代码行中存在逻辑错误:return (start&lt;=0)&amp;&amp;(start&gt;end)? -1: sum;

如果 start 小于 0 或者 start 大于 end,您需要返回 -1,因此应该使用 "||"(逻辑或) 而不是 "&&"(逻辑与):

return (start&lt;=0)||(start&gt;end)? -1: sum;

请参考 @luk2302 的回答,以获得更好的解决方案。

英文:

There is a logic error in your line return (start&lt;=0)&amp;&amp;(start&gt;end)? -1: sum;

You have to return -1 if start is <0 or start > end, so use "||" (logical Or) instead of "&&" (logical and):

return (start&lt;=0)||(start&gt;end)? -1: sum;

Please go through @luk2302's answer for a better solution.

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  • 本文由 发表于 2020年9月10日 18:20:47
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