How to Efficiently Delete Lines from Text Files in C#?

How to efficiently delete text file lines in C#

Deleting specific lines from a text file is a common task in programming. For large files, an efficient approach in C# is to create a temporary file and rewrite the contents of the original file into the temporary file while excluding unnecessary lines. The following code demonstrates this approach:

<code class="language-csharp">string tempFile = Path.GetTempFileName();

using (var sr = new StreamReader("file.txt"))
using (var sw = new StreamWriter(tempFile))
{
    string line;

    while ((line = sr.ReadLine()) != null)
    {
        if (line != "removeme")
            sw.WriteLine(line);
    }
}

File.Delete("file.txt");
File.Move(tempFile, "file.txt");</code>

However, for smaller text files, a simpler, direct execution and less memory intensive approach is preferable:

<code class="language-csharp">File.WriteAllLines(fileName,
    File.ReadLines(fileName).Where(l => l != "removeme").ToList());</code>

It is important to note that all examples assume that the text file uses UTF-8 encoding.

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