C# 类不能从同一文件夹中使用

我刚刚开始学习C和Microsoft Visual Studio。我刚刚创建了一个C控制台应用程序项目，它有一个program.cs文件。我修改了它的内容如下：

using System;

namespace Calculator
{
    class Calculator
    {
        public static double DoOperation(double num1, double num2, string op)
        {
            double result = double.NaN; // Default value is "not-a-number" which we use if an operation, such as division, could result in an error

            // Use a switch statement to do the math
            switch (op)
            {
                case "a":
                    result = num1 + num2;
                    break;
                case "s":
                    result = num1 - num2;
                    break;
                case "m":
                    result = num1 * num2;
                    break;
                case "d":
                    // Ask the user to enter a non-zero divisor
                    if (num2 != 0)
                    {
                        result = num1 / num2;
                    }
                    break;
                // Return text for an incorrect option entry
                default:
                    break;
            }
            return result;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
         //   NewClass obj = NewClass(); //this line is causing problem
            bool endApp = false;
            // Display title as the C# console calculator app
            Console.WriteLine("Console Calculator in C#\r");
            Console.WriteLine("------------------------\n");

            while (!endApp)
            {
                // Declare variables and set to empty
                string numInput1 = "";
                string numInput2 = "";
                double result = 0;

                // Ask the user to type the first number
                Console.Write("Type a number, and then press Enter: ");
                numInput1 = Console.ReadLine();

                double cleanNum1 = 0;
                while (!double.TryParse(numInput1, out cleanNum1))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput1 = Console.ReadLine();
                }

                // Ask the user to type the second number
                Console.Write("Type another number, and then press Enter: ");
                numInput2 = Console.ReadLine();

                double cleanNum2 = 0;
                while (!double.TryParse(numInput2, out cleanNum2))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput2 = Console.ReadLine();
                }

                // Ask the user to choose an operator
                Console.WriteLine("Choose an operator from the following list:");
                Console.WriteLine("\ta - Add");
                Console.WriteLine("\ts - Subtract");
                Console.WriteLine("\tm - Multiply");
                Console.WriteLine("\td - Divide");
                Console.Write("Your option? ");

                string op = Console.ReadLine();

                try
                {
                    result = Calculator.DoOperation(cleanNum1, cleanNum2, op);
                    if (double.IsNaN(result))
                    {
                        Console.WriteLine("This operation will result in a mathematical error.\n");
                    }
                    else Console.WriteLine("Your result: {0:0.##}\n", result);
                }
                catch (Exception e)
                {
                    Console.WriteLine("Oh no! An exception occurred trying to do the math.\n - Details: " + e.Message);
                }

                Console.WriteLine("------------------------\n");

                // Wait for the user to respond before closing
                Console.Write("Press 'n' and Enter to close the app, or press any other key and Enter to continue: ");
                if (Console.ReadLine() == "n") endApp = true;

                Console.WriteLine("\n"); // Friendly linespacing
            }
            return;
        }
    }
}

现在，我想在此项目中添加另一个C文件，并在我的程序中使用该类，如下所示：

using System;

namespace Calculator
{
    class Calculator
    {
        public static double DoOperation(double num1, double num2, string op)
        {
            double result = double.NaN; // Default value is "not-a-number" which we use if an operation, such as division, could result in an error

            // Use a switch statement to do the math
            switch (op)
            {
                case "a":
                    result = num1 + num2;
                    break;
                case "s":
                    result = num1 - num2;
                    break;
                case "m":
                    result = num1 * num2;
                    break;
                case "d":
                    // Ask the user to enter a non-zero divisor
                    if (num2 != 0)
                    {
                        result = num1 / num2;
                    }
                    break;
                // Return text for an incorrect option entry
                default:
                    break;
            }
            return result;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
         //   NewClass obj = NewClass(); //this line is causing problem
            bool endApp = false;
            // Display title as the C# console calculator app
            Console.WriteLine("Console Calculator in C#\r");
            Console.WriteLine("------------------------\n");

            while (!endApp)
            {
                // Declare variables and set to empty
                string numInput1 = "";
                string numInput2 = "";
                double result = 0;

                // Ask the user to type the first number
                Console.Write("Type a number, and then press Enter: ");
                numInput1 = Console.ReadLine();

                double cleanNum1 = 0;
                while (!double.TryParse(numInput1, out cleanNum1))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput1 = Console.ReadLine();
                }

                // Ask the user to type the second number
                Console.Write("Type another number, and then press Enter: ");
                numInput2 = Console.ReadLine();

                double cleanNum2 = 0;
                while (!double.TryParse(numInput2, out cleanNum2))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput2 = Console.ReadLine();
                }

                // Ask the user to choose an operator
                Console.WriteLine("Choose an operator from the following list:");
                Console.WriteLine("\ta - Add");
                Console.WriteLine("\ts - Subtract");
                Console.WriteLine("\tm - Multiply");
                Console.WriteLine("\td - Divide");
                Console.Write("Your option? ");

                string op = Console.ReadLine();

                try
                {
                    result = Calculator.DoOperation(cleanNum1, cleanNum2, op);
                    if (double.IsNaN(result))
                    {
                        Console.WriteLine("This operation will result in a mathematical error.\n");
                    }
                    else Console.WriteLine("Your result: {0:0.##}\n", result);
                }
                catch (Exception e)
                {
                    Console.WriteLine("Oh no! An exception occurred trying to do the math.\n - Details: " + e.Message);
                }

                Console.WriteLine("------------------------\n");

                // Wait for the user to respond before closing
                Console.Write("Press 'n' and Enter to close the app, or press any other key and Enter to continue: ");
                if (Console.ReadLine() == "n") endApp = true;

                Console.WriteLine("\n"); // Friendly linespacing
            }
            return;
        }
    }
}

使用制度

namespace Calculator
{
    public class NewClass
    {
        public NewClass()
        {
            Console.WriteLine("Hello World");
        }
    }
}

当我试图在程序中使用NewClass时，它给出了一个错误。我已经将它添加到program.cs所在的同一个文件夹中，但它仍然没有修复。我从中得到了这个解决方案

因此，我的主要问题是：

如何在c中使用来自同一文件夹的其他类就像在java中一样，如果两个程序在同一文件夹中，它们被认为是在同一个包中，并且可以在没有任何导入语句的情况下使用。在这种情况下就不能这样做吗？ 这与当前主题无关，但是我们可以在Microsoft Visual studio中创建一个项目吗？它只是一个包含一些C文件的文件夹？更具体地说，我只想像在普通IDE中一样编写C代码，如何在不创建任何项目的情况下完成？ 编辑：我应该把确切的错误贴出来……我的错。 因此，当我试图运行程序时，它显示：

1>------ Build started: Project: ConsoleApp1, Configuration: Debug|AnyCPU ------
C:\Users\<SystemName>\Source\Repos\<UserName>\C-sharp-Practice-Codes\ConsoleApp1\ConsoleApp1\Program.cs(42,28,42,36): error CS1955: Non-invocable member 'NewClass' cannot be used like a method.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

为什么NewClass不可开票

如何在c中使用来自同一文件夹的其他类就像在java中一样，如果两个程序在同一文件夹中，它们被认为是在同一个包中，并且可以在没有任何导入语句的情况下使用。在这种情况下就不能这样做吗

你刚刚错过了新接线员。您与NewClass的连线应如下所示：

using System;

namespace Calculator
{
    class Calculator
    {
        public static double DoOperation(double num1, double num2, string op)
        {
            double result = double.NaN; // Default value is "not-a-number" which we use if an operation, such as division, could result in an error

            // Use a switch statement to do the math
            switch (op)
            {
                case "a":
                    result = num1 + num2;
                    break;
                case "s":
                    result = num1 - num2;
                    break;
                case "m":
                    result = num1 * num2;
                    break;
                case "d":
                    // Ask the user to enter a non-zero divisor
                    if (num2 != 0)
                    {
                        result = num1 / num2;
                    }
                    break;
                // Return text for an incorrect option entry
                default:
                    break;
            }
            return result;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
         //   NewClass obj = NewClass(); //this line is causing problem
            bool endApp = false;
            // Display title as the C# console calculator app
            Console.WriteLine("Console Calculator in C#\r");
            Console.WriteLine("------------------------\n");

            while (!endApp)
            {
                // Declare variables and set to empty
                string numInput1 = "";
                string numInput2 = "";
                double result = 0;

                // Ask the user to type the first number
                Console.Write("Type a number, and then press Enter: ");
                numInput1 = Console.ReadLine();

                double cleanNum1 = 0;
                while (!double.TryParse(numInput1, out cleanNum1))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput1 = Console.ReadLine();
                }

                // Ask the user to type the second number
                Console.Write("Type another number, and then press Enter: ");
                numInput2 = Console.ReadLine();

                double cleanNum2 = 0;
                while (!double.TryParse(numInput2, out cleanNum2))
                {
                    Console.Write("This is not valid input. Please enter an integer value: ");
                    numInput2 = Console.ReadLine();
                }

                // Ask the user to choose an operator
                Console.WriteLine("Choose an operator from the following list:");
                Console.WriteLine("\ta - Add");
                Console.WriteLine("\ts - Subtract");
                Console.WriteLine("\tm - Multiply");
                Console.WriteLine("\td - Divide");
                Console.Write("Your option? ");

                string op = Console.ReadLine();

                try
                {
                    result = Calculator.DoOperation(cleanNum1, cleanNum2, op);
                    if (double.IsNaN(result))
                    {
                        Console.WriteLine("This operation will result in a mathematical error.\n");
                    }
                    else Console.WriteLine("Your result: {0:0.##}\n", result);
                }
                catch (Exception e)
                {
                    Console.WriteLine("Oh no! An exception occurred trying to do the math.\n - Details: " + e.Message);
                }

                Console.WriteLine("------------------------\n");

                // Wait for the user to respond before closing
                Console.Write("Press 'n' and Enter to close the app, or press any other key and Enter to continue: ");
                if (Console.ReadLine() == "n") endApp = true;

                Console.WriteLine("\n"); // Friendly linespacing
            }
            return;
        }
    }
}

NewClass obj=新的NewClass； 在中阅读有关新运算符的更多信息

这与当前主题无关，但是我们可以在Microsoft Visual studio中创建一个项目吗？它只是一个包含一些C文件的文件夹？更具体地说，我只想像在普通IDE中一样编写C代码，如何在不创建任何项目的情况下完成

您可以通过两种方式完成此操作：

通过在新的项目窗口中创建空白解决方案，创建者可以了解这一点； 通过打开任何目录（如编程编辑器中的目录），您可以通过解决方案资源管理器轻松创建新文件。

---

错误是什么？请以文本形式发布，而不是截图形式发布。这是一个错误。你把车交给修理工，说它坏了。你认为机修工能用这些信息修好你的车吗？如果需要帮助，您需要提供具体的详细信息，说明哪些内容不起作用。您错过了新的操作员。NewClass obj=新的NewClass@我真为我愚蠢的错误感到羞愧。谢谢你指出。现在已经修好了…：你能解释一下第二个问题吗？如果你熟悉Java，你也可以这样做。只需创建一个扩展名为.cs的文本文件，并使用csc.exe编译器构建它即可。请参见：