C# if-else语句和while循环

请看一下下面的代码

namespace Funny
{
    class QuesionsAndAnswers
    {
        private double firstNumber;
        private double secondNumber;
        private double userAnswer;
        private double computerAnswer;

        private string operators;

        private bool answerCorrect;
        private bool enableDouble;

        private double[] listOfNumbers;
        private string[] listOfOperators;

        private Random randomizer;

        private static QuesionsAndAnswers qa;

        private QuesionsAndAnswers()
        {
            randomizer = new Random();

            listOfNumbers = new double[] { 1,2,3,4,5,6,7,8,9 };
            listOfOperators = new string[] { "+", "-", "*", "/" };
        }

        public static QuesionsAndAnswers getQuesionsandAnswersInstance()
        {
            if (qa == null)
                qa = new QuesionsAndAnswers();
             return qa;
        }

        public string generateQuestions()
        {
            string result = "";

            operators = listOfOperators[randomizer.Next(listOfOperators.Length)];
            firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
            secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];

            if ((operators.Equals("/")) && (enableDouble == false))
            {
                while (firstNumber % secondNumber == 0)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            else if (operators.Equals("-") && (firstNumber<secondNumber))
            {
                while (firstNumber > secondNumber)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                    secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            return result;
        }

        public void setDoubleAnswers(bool check)
        {
            enableDouble = check;
        }
    }
}

名称空间
{
课堂提问和答案
{
私人双第一号码；
私人双倍号码；
私人双用户应答；
私人双机应答；
私有字符串运算符；
私人布尔回答正确；
私人布尔使能双；
私人双[]号码列表；
私有字符串[]listOfOperators；
私有随机发生器；
私人静态问答；
私人问题和答案（）
{
随机发生器=新随机（）；
listOfNumbers=新的双[]{1,2,3,4,5,6,7,8,9}；
listOfOperators=新字符串[]{“+”，“-”，“*”，“/”}；
}
公共静态问题和答案获取问题和答案立场（）
{
如果（qa==null）
qa=新问题和答案（）；
返回qa；
}
公共字符串generateQuestions（）
{
字符串结果=”；
operators=listOfOperators[randomizer.Next（listOfOperators.Length）]；
firstNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
secondNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
if（（运算符.Equals（“/”）&&（enableDouble==false））
{
while（firstNumber%secondNumber==0）
{
firstNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
}
结果=第一个数字+运算符+第二个数字；
}
else if（运算符。等于（“-”&&（第一个数字第二个数字）
{
firstNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
secondNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
}
结果=第一个数字+运算符+第二个数字；
}
返回结果；
}
公共无效设置双重应答（布尔检查）
{
enableDouble=检查；
}
}
}

在这里，在generateQuestions（）方法中，我试图生成一些数学问题

如果运算符在“-”中，并且第一个数字<第二个数字，则应重新生成数字（第一个数字和第二个数字），以确保答案不是负值

并且，如果运算符为“/”且布尔值为false，则应再次重新生成数字，以确保答案（这意味着计算，例如2/1=2）不包含任何浮点（这意味着不应生成2/3这样的问题，因为答案包含浮点）

在我的尝试中，以上两种情况都没有发生。它仍然会产生意外的答案，有时甚至什么都没有。为什么会这样？请帮助

---

请注意，我是一名Java开发人员，这是我的第一个主要C#项目。

您的

语句中有错误的条件，而
语句中应该有完全相反的条件。此外，如果所有条件都不匹配，您也不会为结果赋值，因此
result=firstNumber+operators+secondNumber；
行应该是m已从条件语句中删除（或仅替换为简单返回）：

。。。
if（（运算符.Equals（“/”）&&（enableDouble==false））
{
而（firstNumber%secondNumber！=0）//
应该是

while (firstNumber % secondNumber != 0)

只要您提供的条件为
true
，则
while
循环将继续执行。因为您希望firstNumber%secondNumber等于0；只要
firstNumber%secondNumber！=0，就应该循环并生成新值

我相信减法循环也有同样的问题

最后（与您的问题无关）您可以使用
=
来比较C#中的字符串

嗯，它有时不返回任何内容，因为除了要捕获的边缘情况之外，您从未将
结果设置为
“
以外的任何内容

你的
while
语句都是错误的。应该是：

while ((firstNumber % secondNumber) != 0)
:
while (firstNumber < secondNumber)

你有
a=21，b=7
，它保证给出一个整数乘法器，并给出等式
“21/7”


因此，这（psuedo代码）是我首先要做的：

# Get the random values.

op = random_from ("+-/*")
n1 = random_from ("123456789")
n2 = random_from ("123456789")

# For subtraction, make sure n1 >= n2.

if op = "-" and n1 < n2:
    tmp = n1;
    n1 = n2;
    n2 = tmp;

# For division, make sure n1 is integral multiplier of n2.

if op = "/":
    n1 = n1 * n2

# Return expression in ALL cases.

return n1 + op + n2

#获取随机值。
op=随机_，从（“+-/*”）
n1=来自（“123456789”）的随机_
n2=来自（“123456789”）的随机变量
#对于减法，请确保n1>=n2。
如果op=“-”和n1
在这两种情况下，虽然您的条件是错误的，但您需要将其更改为

while (firstNumber % secondNumber != 0) 

及

while（firstNumber
以下是我从您的问题中了解到的解决方案

if ((operators.Equals("/")) && (enableDouble == false))
    {
        while (firstNumber % secondNumber != 0)
        {
            firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
        }

        result = firstNumber + operators + secondNumber;

   }
            else if (operators.Equals("-") && (firstNumber<secondNumber))
            {
                while (firstNumber < secondNumber)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                    secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }

                result = firstNumber + operators + secondNumber;
            }

if（（operators.Equals（“/”）&&（enableDouble==false））
{
while（firstNumber%secondNumber！=0）
{
firstNumber=ListOfNumber[randomizer.Next（ListOfNumber.Length）]；
}
结果=第一个数字+运算符+第二个数字；
}
else if（运算符。等于（“-”&&（firstNumber
通过制作两个不同的测试项目来实现测试用例
使用包含这些测试用例的MSVS单元测试项目报告
在第一种情况下报告测试覆盖率，考虑MCDC，在第二种情况下报告总体覆盖率，并对发现不同覆盖率指标的原因进行评论
对于下面的代码

    namespace Funny
    {
    class QuesionsAndAnswers
    {
        private double firstNumber;
        private double secondNumber;
        private double userAnswer;
        private double computerAnswer;

        private string operators;

        private bool answerCorrect;
        private bool enableDouble;

        private double[] listOfNumbers;
        private string[] listOfOperators;

        private Random randomizer;

        private static QuesionsAndAnswers qa;

        private QuesionsAndAnswers()
        {
            randomizer = new Random();

            listOfNumbers = new double[] { 1,2,3,4,5,6,7,8,9 };
            listOfOperators = new string[] { "+", "-", "*", "/" };
        }

        public static QuesionsAndAnswers getQuesionsandAnswersInstance()
        {
            if (qa == null)
                qa = new QuesionsAndAnswers();
             return qa;
        }

        public string generateQuestions()
        {
            string result = "";

            operators = listOfOperators[randomizer.Next(listOfOperators.Length)];
            firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
            secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];

            if ((operators.Equals("/")) && (enableDouble == false))
            {
                while (firstNumber % secondNumber == 0)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            else if (operators.Equals("-") && (firstNumber<secondNumber))
            {
                while (firstNumber > secondNumber)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                    secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            return result;
        }

        public void setDoubleAnswers(bool check)
        {
            enableDouble = check;
        }
    }
    }

名称空间
{
课堂提问和答案
{
私人双第一号码；
私人双倍号码；
私人双用户应答；
私人双机应答；
私有字符串运算符；
私人布尔回答正确；
私有布尔使能
# Get the random values.

op = random_from ("+-/*")
n1 = random_from ("123456789")
n2 = random_from ("123456789")

# For subtraction, make sure n1 >= n2.

if op = "-" and n1 < n2:
    tmp = n1;
    n1 = n2;
    n2 = tmp;

# For division, make sure n1 is integral multiplier of n2.

if op = "/":
    n1 = n1 * n2

# Return expression in ALL cases.

return n1 + op + n2

while (firstNumber % secondNumber != 0) 

while (firstNumber < secondNumber)

if ((operators.Equals("/")) && (enableDouble == false))
    {
        while (firstNumber % secondNumber != 0)
        {
            firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
        }

        result = firstNumber + operators + secondNumber;

   }
            else if (operators.Equals("-") && (firstNumber<secondNumber))
            {
                while (firstNumber < secondNumber)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                    secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }

                result = firstNumber + operators + secondNumber;
            }

    namespace Funny
    {
    class QuesionsAndAnswers
    {
        private double firstNumber;
        private double secondNumber;
        private double userAnswer;
        private double computerAnswer;

        private string operators;

        private bool answerCorrect;
        private bool enableDouble;

        private double[] listOfNumbers;
        private string[] listOfOperators;

        private Random randomizer;

        private static QuesionsAndAnswers qa;

        private QuesionsAndAnswers()
        {
            randomizer = new Random();

            listOfNumbers = new double[] { 1,2,3,4,5,6,7,8,9 };
            listOfOperators = new string[] { "+", "-", "*", "/" };
        }

        public static QuesionsAndAnswers getQuesionsandAnswersInstance()
        {
            if (qa == null)
                qa = new QuesionsAndAnswers();
             return qa;
        }

        public string generateQuestions()
        {
            string result = "";

            operators = listOfOperators[randomizer.Next(listOfOperators.Length)];
            firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
            secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];

            if ((operators.Equals("/")) && (enableDouble == false))
            {
                while (firstNumber % secondNumber == 0)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            else if (operators.Equals("-") && (firstNumber<secondNumber))
            {
                while (firstNumber > secondNumber)
                {
                    firstNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                    secondNumber = listOfNumbers[randomizer.Next(listOfNumbers.Length)];
                }
                result = firstNumber + operators + secondNumber;
            }
            return result;
        }

        public void setDoubleAnswers(bool check)
        {
            enableDouble = check;
        }
    }
    }