如何删除文本文件中某些文本下方的所有行？

Question

我有一个代码，它遍历整个文本文件以搜索特定文本“[names]”，并“尝试”删除文本下方的所有行。我尝试了 File.WriteAllText(INILoc, string.Empty);，但这只会删除整个文本文件中的所有内容。我怎样才能做到只删除“[names]”下面的所有行？

我已经像这样设置了迭代：

string[] lines = File.ReadAllLines(INILoc);
bool containsSearchResul = false;
foreach (string line in lines)
    {
         if (containsSearchResul)
           {
                File.WriteAllText(INILoc, string.Empty);

           }
         if (line.Contains("[names]"))
           {
                containsSearchResul = true;
           }
    }

Answer 1

您需要将"[names]"文本之前的行存储到字符串变量中，当条件(line.Contains("[names]"))满足时，只需中断循环并将字符串值写入同一个文件。

类似的，

string[] lines = File.ReadAllLines(INILoc); //Considering INILoc is a string variable which contains file path.
StringBuilder newText = new StringBuilder();
bool containsSearchResul = false;

foreach (string line in lines)
    {
       newText.Append(line);
       newText.Append(Environment.NewLine); //This will add \n after each line so all lines will be well formatted

       //Adding line into newText before if condition check will add "name" into file
       if (line.Contains("[names]"))
              break;

    }

File.WriteAllText(INILoc, newText.ToString());
                        //^^^^^^^ due to string.Empty it was storing empty string into file.

注意：如果你使用StringBuilder类，那么不要错过在你的程序中添加Using System.Text

Answer 2

使用StreamReader，因为它会为您提供最佳性能，因为您不需要读取整个文件。将“输入文件路径”替换为您的文件路径，结果将存储在您为“输出文件路径”提供的路径中。

using (var sr = new StreamReader("PATH TO INPUT FILE"))
{
    using (var sw = new StreamWriter("PATH TO OUTPUT FILE"))
    {
        var line = sr.ReadLine();

        while (line != null)
        {
            sw.WriteLine(line);

            if (line.Contains("[names]"))
            {
                sw.Close();
                sr.Close();
            }
            else
            {                            
                line = sr.ReadLine();
            }                        
        }
    }
}

如果需要写入同一个文件：

var sb = new StringBuilder();

using (var sr = new StreamReader("PATH TO INPUT FILE"))
{
    var line = sr.ReadLine();

    while (line != null)
    {
        sb.AppendLine(line);

        if (line.Contains("[names]"))
        {
            sr.Close();
        }
        else
        {
            line = sr.ReadLine();
        }
    }
}

File.WriteAllText("PATH TO INPUT FILE", sb.ToString());

Answer 3

根据请求的代码，我已将修改放在一起。

    string[] lines = File.ReadAllLines(INILoc);
    //create a list to hold the lines
    List<string> output = new List<string>();
    //loop through each line
    foreach (string line in lines)
    {
        //add current line to  ouput.
        output.Add(line);
        //check to see if our line includes the searched text;
        if (line.Contains("[names]"))
        {
            //output to the file and then exit loop causing all lines below this 
            //one to be skipped
            File.WriteAllText(INILoc, output.ToArray());
            break;
        }
    }

Answer 4

您的代码的问题在于它删除了[names]之前的所有行，而不是之后（更准确地说，只写该文本之后的行）。此外，任何时候您重写所有文件内容，因此删除所有先前写入的行。它的工作原理如下：

string[] lines = File.ReadAllLines(INILoc);
using (StreamWriter writer = new StreamWriter(INILoc)) // https://docs.microsoft.com/en-us/dotnet/standard/io/how-to-write-text-to-a-file
{
            bool containsSearchResul = false;
            foreach (string line in lines)
            {

                if (!containsSearchResul)
                {
                    writer.Write(INILoc, string.Empty);

                }

                if (line.Contains("[names]"))
                {
                    containsSearchResul = true;
                }
            }
}

您有另一个更好的选择来使用break：

string[] lines = File.ReadAllLines(INILoc);
using (StreamWriter writer = new StreamWriter(INILoc)) // https://docs.microsoft.com/en-us/dotnet/standard/io/how-to-write-text-to-a-file
{
            foreach (string line in lines)
            {
                if (line.Contains("[names]"))
                {
                    break;
                }

                writer.WriteLine(INILoc, string.Empty);
            }
}

但是您可以通过使用 LINQ 以更喜欢、更易读的方式执行此操作：

using System.Linq;

// ...

string[] lines = File.ReadAllLines(INILoc);
string[] linesTillNames = lines
                          .Take( // Take just N items from the array
                              Array.IndexOf(lines, "[names]") // Until the index of [names]
                          )
                          .ToArray();
File.WriteAllLines(INILoc, linesTillNames);

Answer 5

你也可以这样使用：WriteAllLines(string path, IEnumerable<string> contents)：

string[] lines = File.ReadAllLines(INILoc);
List<string> linesToWrite = new List<string>();

foreach(string line in lines)
{
    linesToWrite.Add(line);
    if (line.Contains("[names]")) break;
}

File.WriteAllLines(INILoc, linesToWrite);