C＃StreamWriter无法将类型隐式转换为字符串到SYSTEMS.IO

Question

我需要使用StreamWriter来写入/存储用户输入的信息。 我已经用下面的代码来工作了。

现在，我需要使其写入用户名字的文件，并将信息存储在此文件中。

隐藏展开复制代码

case 2: //enter new user
    //Enter new user information and add them to file
    Console.Write("Please Enter the number of users you wish to log: ");

    iUserNumber = Convert.ToInt32(Console.ReadLine());

    //open file for writing, in APPEND mode
    using (StreamWriter sw = new StreamWriter("NewUser" +sName,".txt", true))
    {
        //loop for each user
        for (iCount = 1; iCount <= iUserNumber; iCount++)
        {
            // enter details
            Console.Write("Please Enter your Name" + iCount + ": ");
            sName = Console.ReadLine();

            Console.Write("Please Enter the Name of your School: ");
            sSchoolName = Console.ReadLine();
            Console.WriteLine();

            Console.Write("Please Enter the Name of your Class: ");
            sClassName = Console.ReadLine();

            // write to file
            sw.WriteLine(sName);
            Console.WriteLine();
            sw.WriteLine(sSchoolName);
            Console.WriteLine();
            sw.WriteLine(sClassName);

            Console.WriteLine("User data entered: ");
        }
    }

我似乎无法使它正常工作并不断提出以下错误：

参数1：无法从“字符串”转换为“ System.IO.Stream” FUNCOCO2

错误CS0165使用未分配的局部变量'sName'FUNCOCO2

错误CS1503参数2：无法从“字符串”转换为“ System.Text.Encoding”

我不确定如何解决此问题。

我将其更改为：

case 2: //enter new user
    //Enter new user information and add them to file
    Console.Write("Please Enter the number of users you wish to log: ");
    iUserNumber = Convert.ToInt32(Console.ReadLine());
    //enter first name
    Console.WriteLine("Please enter your first Name: ");
    sFirstName = Convert.ToString(Console.ReadLine());

    //open file for writing, in APPEND mode
    using (StreamWriter sw = new StreamWriter(sName))
    {
        //loop for each user
        for (iCount = 1; iCount <= iUserNumber; iCount++)
        {
            // enter details
            Console.Write("Please Enter your Name" + iCount + ": ");
            sLastName = Console.ReadLine();

            Console.Write("Please Enter the Name of your School: ");
            sSchoolName = Console.ReadLine();
            Console.WriteLine();

            Console.Write("Please Enter the Name of your Class: ");
            sClassName = Console.ReadLine();

            // write to file
            sw.WriteLine(sName);
            Console.WriteLine();
            sw.WriteLine(sSchoolName);
            Console.WriteLine();
            sw.WriteLine(sClassName);

            Console.WriteLine("User data entered: ");
        }
    }

而且这似乎也不起作用。

Answer 1

对于代码的第一部分，您尝试在将值分配给sName之前打开流写入器。 using关键字只是确保一旦代码退出该部分，对象就可以正确放置，这意味着在这种情况下，您不会在所有位置打开文件。 您应该做的是在for循环中打开一个文件。 正确的代码是：

   case 2: //enter new user
            //Enter new user information and add them to file
            Console.Write("Please Enter the number of users you wish to log: ");
            iUserNumber = Convert.ToInt32(Console.ReadLine());



                //loop for each user
                for (iCount = 1; iCount <= iUserNumber; iCount++)
                {
                    // enter details
                    Console.Write("Please Enter your Name" + iCount + ": ");
                    sName = Console.ReadLine();

                    Console.Write("Please Enter the Name of your School: ");
                    sSchoolName = Console.ReadLine();
                    Console.WriteLine();

                    Console.Write("Please Enter the Name of your Class: ");
                    sClassName = Console.ReadLine();

                    // write to file
                    //open file for writing, in APPEND mode
                    using (StreamWriter sw = new StreamWriter("NewUser" +sName +".txt", true))
                    {
                        sw.WriteLine(sName);
                        Console.WriteLine();
                        sw.WriteLine(sSchoolName);
                        Console.WriteLine();
                        sw.WriteLine(sClassName);
                    }


                    Console.WriteLine("User data entered: ");

                }

            }

编辑：加号，整个'，'，而不是流式编写器开头的'+'。 我想念那明显的东西。

Answer 2

using (StreamWriter sw = new StreamWriter("NewUser" +sName,".txt", true))

+ sName后面似乎还有一个逗号。 该逗号应为+，以将3个字符串部分连接在一起

像这样using (StreamWriter sw = new StreamWriter("NewUser" + sName + ".txt", true))

Argument 1: cannot convert from 'string' to 'System.IO.Stream' FUNCOCO2

Error CS0165 Use of unassigned local variable 'sName' FUNCOCO2

Error CS1503 Argument 2: cannot convert from 'string' to 'System.Text.Encoding'

错误1，因为““ NewUser” + sName“不是有效的文件路径，因此不能是流

错误2因为...不知道，因为我看不到您在哪里声明sName

错误3，因为...多余的逗号正在更改您真正要使用的构造函数，该多余的逗号将“ .txt”转换为所需的无效编码。

Answer 3

按照错误消息进行操作（如果双击它们，它们将指向特定的行号），读取错误，然后更正错误。

---

错误CS0165使用未分配的局部变量'sName'FUNCOCO2

在流sName中使用sName之前，您永远不会定义和分配它。 如果要为每个用户创建1个文件，则需要更改逻辑以反映该逻辑，并在循环内而不是循环外创建一个新的streamwriter。

---

参数1：无法从“字符串”转换为“ System.IO.Stream”

new StreamWriter("NewUser" +sName,".txt", true))

应该

new StreamWriter("NewUser" +sName + ".txt", true))

确实接受字符串作为第一个参数。

---

评论谢谢，然后我如何让StreamReader打开该文件？

您需要将循环放在流编写器的创建之外。

//loop for each user
for (iCount = 1; iCount <= iUserNumber; iCount++)
{
    Console.Write("Please Enter your Name" + iCount + ": ");
    var sName = Console.ReadLine(); // remove the previous instance you had of sName and make it a scoped variable to the for loop
    using (StreamWriter sw = new StreamWriter("NewUser" +sName + ".txt", true))
    { /*use the streamwriter here */ }
}

Answer 4

您可以执行以下操作：

Console.WriteLine("Please enter your first Name: ");
            String sFirstName = Console.ReadLine();
            String information = String.Empty;
            String append = String.Empty;

            while (true)
            {

                Console.Write("Please Enter your Name: ");
                information = information + Console.ReadLine() + " ";

                Console.Write("Please Enter the Name of your School: ");
                information = information + Console.ReadLine() + " ";

                if (information.Trim().Equals(""))
                {
                    break;
                }

                Console.Write("Please Enter the Name of your Class: ");
                information = information + Console.ReadLine() + "\t";

                append = append + information;
                information = String.Empty;


            }

            String fileLocation = "C:...\\New Text Document.txt";


            using (StreamWriter sw = new StreamWriter(fileLocation))
            {
                // write to file
                sw.WriteLine(append);
                Console.WriteLine("User data entered: ");

            }