How to overwrite a line in a file?

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Good day,
I have a question about rewriting the text in the line I'm looking for. The code works if I write the line number, but as soon as I try to find the line number, I don't know how.

I will be happy for any advice and help.

Thank you very much.

What I have tried:

C#

public MainWindow()
       {
           InitializeComponent();
       }

       private void Grid_Loaded(object sender, RoutedEventArgs e)
       {
           TextBox.Focus();
       }

       private void HledatButton_Click(object sender, RoutedEventArgs e)
       {
           string file = TextBox.Text;
           List<string> files = Directory.GetFiles(file, "*.csproj", SearchOption.AllDirectories).ToList();
          foreach (string pathFile in files)
           {
               string[] lines = File.ReadAllLines(pathFile);

               var newText = "";
               var oldText = "";
               int lineEdit =0;
               foreach (string object in lines)
               {
                   if (objekt.Contains(oldText))
                   {
                       lineEdit++;

                   }
                   lines[lineEdit - 1] = newText;
                   File.WriteAllLines(pathFile, lines);
               }

           }


       }

Application is in c# and WPF

Posted 5-Nov-21 0:59am

dejf111

Updated 5-Nov-21 1:14am

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Comments

BillWoodruff 5-Nov-21 7:15am

put breakpoints in your code; single-step through it using F11, examine the values of variables ,,, that will show you what the problem is.

PIEBALDconsult 5-Nov-21 11:32am

"Editing" text files is fraught with peril. Basically, don't try.
I recommend using an XmlDocument to read/load the file. Use XPath to find what you want to change. Make the change. Then write the file.
Further, I would write the new file as a .tmp, rename the existing file as .bak, and then rename the .tmp -- so you still have a backup in case something went wrong.

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Richard Deeming · Accepted Answer · 2021-11-05T01:14:00

Use a for loop instead of a foreach loop, and only write the updated content back to the file outside of the loop.

C#

for (int index = 0; index < lines.Length; index++)
{
    string line = lines[index];
    if (line.Contains(oldText))
    {
        lines[index] = newText;
    }
}

File.WriteAllLines(pathFile, lines);

NB: Since csproj files are XML, it may be safer to load and manipulate them using an XML parser - eg: LINQ to XML[^].