如何在文本文件中上下移动项目

How do I move items/values up and down a text file. At the moment my program reads a text file, an uses a while to make sure it stop when there is no more lines to read. I used an if statement to check if counter equals the line of the value I want to move. I am stuck not sure how to continue from here.

如何上下移动文本文件中的项/值。当我的程序读取一个文本文件时，an会用一段时间来确保当没有更多的行可以读取时它会停止。我使用if语句检查counter是否等于我要移动的值的行。我不知道该如何从这里继续下去。

  _upORDown = 1; 

    using (StreamReader reader = new StreamReader("textfile.txt"))
    {
        string line = reader.ReadLine();
        int Counter = 1;
        while (line != null)
        {

            if (Counter == _upORDown)
            {
              //Remove item/replace position

            }
            Counter++;
        }
    }

2 个解决方案

#1

You can read the file in memory, move the line to where you need it, and write the file back. You can use ReadAllLines and WriteAllLines.

您可以在内存中读取文件，将该行移动到需要它的位置，并将文件写回。您可以使用ReadAllLines和WriteAllLines。

This code moves the string at position i up by one line:

此代码将字符串在位置i上移动一行:

if (i == 0) return; // Cannot move up line 0
string path = "c:\\temp\\myfile.txt";
// get the lines
string[] lines = File.ReadAllLines(path);
if (lines.Length <= i) return; // You need at least i lines
// Move the line i up by one
string tmp = lines[i];
lines[i] = lines[i-1];
lines[i-1] = tmp;
// Write the file back
File.WriteAllLines(path, lines);

#2

@dasblinkenlight's answer, using LINQ:

使用LINQ @dasblinkenlight的回答:

string path = "c:\\temp\\myfile.txt";
var lines = File.ReadAllLines(path);
File.WriteAllLines(
    path,
    lines.Take(i).Concat(
        lines.Skip(i+1)
    )
);

This deletes the line at position i (zero-based) and moves the other lines up.

这将删除位置i(基于零的)的行，并将其他行向上移动。

Adding to a new line:

增加一条新线路:

string path = "c:\\temp\\myfile.txt";
var lines = File.ReadAllLines(path);
var newline = "New line here";
File.WriteAllLines(
    path,
    lines.Take(i).Concat(
        new [] {newline}
    ).Concat(
        lines.Skip(i+1)
    )
);

#1