在 C# 中使用 bool 时，while 循环不起作用答案

【问题标题】：While loop not working while using bool in C#在 C# 中使用 bool 时，while 循环不起作用
【发布时间】：2014-04-28 02:00:36
【问题描述】：

我的 while 循环不工作。菜单上有 3 个选项，用户不断输入输入，直到按下“esc”。但是程序在用户输入其中一个选项后退出，并且不会返回菜单。如何修复我的 while 循环？请帮忙。

bool runApp = false;//menu.cs #12 Need to false sinces the loop is true
        Student[] students = new Student[35];
        //Application loop
        while (runApp);
        {
            Console.Clear();
            Console.WriteLine("\n\tGrade Book Menu\n");
            Console.WriteLine("\t1) Add Student");
            Console.WriteLine("\t2) Enter Student Grades");
            Console.WriteLine("\t3) List Student Grades");
            Console.Write("\nEnter Selection or Press Escape to exit: ");
            ConsoleKeyInfo key = Console.ReadKey();
            if (key.Key == ConsoleKey.Escape)
            {
                runApp = false;
            }
            else
            {
                switch (key.Key)
                {
                    case ConsoleKey.NumPad1:
                    case ConsoleKey.D1:
                        //Get the current student count stored in the Student Class variable
                        int indexForNewStudent = Student.GetStudentCount();
                        indexForNewStudent = 0;
                        Console.Write("\nEnter Student Name: ");
                        //Instantiate a Student object and place it in the array of Student objects called student
                        students[indexForNewStudent] = new Student(Console.ReadLine()); //Call overloaded constructor
                        //Increment Student count
                        Student.SetStudentCount(indexForNewStudent + 2); //Add to index to account for new student
                        break;
                    case ConsoleKey.NumPad2:
                    case ConsoleKey.D2:
                        Console.WriteLine("\nEnter the Student Number.  Use List Students to get Student Number.");
                        int studentNumber = 0; //Temporary variable to hold the student number to enter grades
                        //Test the entered string is a number and between 1 and 30
                        if ((int.TryParse(Console.ReadLine(), out studentNumber)) && (studentNumber <= 1) &&
                             (studentNumber >= 30))
                        {
                            //In the event a student has not been added this code will crash
                            if (Student.GetStudentCount() < 0) //Has a student been added?
                                students[studentNumber - 1].EnterStudentScores(); //Subtract 1 from enterd number for array index
                            else
                                Console.WriteLine("A student has not been added");
                        }
                        else
                        {
                            Console.WriteLine("Invalid Student Number.  Enter a number from 1 to 30");
                        }
                        break;
                    case ConsoleKey.NumPad3:
                    case ConsoleKey.D3:
                        Student.ListStudents(students);
                        break;
                    default:
                        Console.WriteLine("Invalid Menu Selection");
                        break;
                }
                Console.Write("Press a key to return to Menu");
                Console.ReadKey();
            }
        }
        Console.Write("\nExiting Application.  Press any key to close window... ");
        Console.ReadKey();

【问题讨论】：

这根本不应该工作。在点击 while 循环之前，您的布尔标志设置为 false...
你知道 while 循环是如何工作的吗？

标签： c# while-loop boolean

【解决方案1】：

你有两个问题：

“runApp”变量需要初始化为真。这允许循环运行，直到“escape”键将其设置为 false。
删除while(runApp) 之后的分号。这会导致循环一直旋转，直到条件为假（这可能是变量首先设置为假的原因）。删除它允许执行 {} 中的代码，直到条件变为 false（这发生在按下退出键时。

如果我能澄清这些，请告诉我！

【讨论】：

【解决方案2】：

将 runApp 初始化为 true 并通过删除分号“;”来修复此行

while (runApp);

应该是

while (runApp)

【讨论】：

【解决方案3】：

将runApp改为true：

bool runApp = true;

【讨论】：

这错过了while循环后的分号
这还不够。在 while 语句之后还有一个分号。

【解决方案4】：

问题出在第一行：

bool runApp = true; //this condition needs to be true or it won't enter
        Student[] students = new Student[35];
        //Application loop
        while (runApp) //you need no ";" or it won't execute the loop

runApp 必须为真；
您需要删除分号，否则括号中的代码不会循环。

【讨论】：