Question

C＃我有一个控制台应用程序，可以读取和写入“人员”详细信息的获取/设置列表。它正常工作，直到我尝试将其写入文本文件。有人可以告诉我为什么将“Person”细节的最后一行写入我的文本文件而不是整个列表？

        loadData();

        Console.WriteLine("All People");
        //1st query - just select all people
        var queryAllPeople = from person in people  select person;

        foreach (Person p in queryAllPeople)
        {
            using (StreamWriter writer = new StreamWriter("people.txt"))
            {

                writer.WriteLine(p);

            }
            Console.WriteLine(p);
        }

        Console.ReadLine();

Answer 1

将foreach放在using语句中。您在循环的每次迭代中都会覆盖该文件

Answer 2

您正在为每次迭代编写一个具有相同名称的新文件。您需要在循环外创建StreamWriter：

using (StreamWriter writer = new StreamWriter("people.txt"))
{
    foreach (Person p in queryAllPeople)
    {
        writer.WriteLine(p);
        Console.WriteLine(p);
    }
}

Answer 3

您每次都在重新创建文件。尝试：

using (StreamWriter writer = new StreamWriter("people.txt"))
{
    foreach (Person p in queryAllPeople)
    {
        writer.WriteLine(p);
        Console.WriteLine(p);
    }

}

Answer 4

使用接受附加作为参数的StreamWriter重载，以便附加每次都是文件的值。

foreach (Person p in queryAllPeople)
{
  using (StreamWriter writer = new StreamWriter("people.txt", true))
  {

     writer.WriteLine(p);

  }
  Console.WriteLine(p);
}

或者只是将foreach包装在using语句中。

StreamWriter将所有行传递给文件

4 个答案: