Removing the first line of a text file in C#

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I can currently remove the last line of a text file using:

    var lines = System.IO.File.ReadAllLines("test.txt");
    System.IO.File.WriteAllLines("test.txt", lines.Take(lines.Length - 1).ToArray());

Although, how is it possible to instead remove the beginning of the text file?


Instead of lines.Take, you can use lines.Skip, like:

var lines = File.ReadAllLines("test.txt");
File.WriteAllLines("test.txt", lines.Skip(1).ToArray());

to truncate at the beginning despite the fact that the technique used (read all text and write everything back) is very inefficient.

About the efficient way: The inefficiency comes from the necessity to read the whole file into memory. The other way around could easily be to seek in a stream and copy the stream to another output file, delete the original, and rename the old. That one would be equally fast and yet consume much less memory.

Truncating a file at the end is much easier. You can just find the trunaction position and call FileStream.SetLength().

how to delete first line in a txt file, Basically you need to copy it to another file - you can't remove (or insert) data in a file "in place". For example, in .NET 4 it's easy: var lines = File  For a project that I am doing, one of the things that I must do is delete the first X lines of a plaintext file. I'm saying X because I will need to do this routine multiple times and each time, the lines to delete will be different, but they will always start from the beginning, delete the first X and then output the results to the same file.


var lines = System.IO.File.ReadAllLines("test.txt");
System.IO.File.WriteAllLines("test.txt", lines.Skip(1).ToArray());

Skip eliminates the given number of elements from the beginning of the sequence. Take eliminates all but the given number of elements from the end of the sequence.

c# code to delete first file from a txt file - MSDN, ok load the file in and write it back out missing the first line - like this: private void RemoveFirstLine(string filePath) { FileStream fs = new  First you load the text file into a string. Then you split it by the line separator into an array of strings. Then write the array to the file line by line, starting at the xth (since c# is has 0 based arrays, the first x lines are 0 to x-1). This solution is more optimal than modifying the array by copying the lines from x to the last line to another array, and then writing the array.


Here is an alternative:

        using (var stream = File.OpenRead("C:\\yourfile"))
        {
            var items = new LinkedList<string>();
            using (var reader = new StreamReader(stream))
            {
                reader.ReadLine(); // skip one line
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    //it's far better to do the actual processing here
                    items.AddLast(line);
                }
            }
        }

Update

If you need an IEnumerable<string> and don't want to waste memory you could do something like this:

    public static IEnumerable<string> GetFileLines(string filename)
    {
        using (var stream = File.OpenRead(filename))
        {
            using (var reader = new StreamReader(stream))
            {
                reader.ReadLine(); // skip one line
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    yield return line;
                }
            }
        }
    }


    static void Main(string[] args)
    {
        foreach (var line in GetFileLines("C:\\yourfile.txt"))
        {
            // do something with the line here.
        }
    }

How to remove a line from Text File using C#, Loop over all lines and create a copy of the original lines where you leave away the matching lines. Something like this in LINQ (or you may  The best way to do this is to open the file in text mode, read each line with ReadLine(), and then write it to a new file with WriteLine(), skipping the one line you want to delete. There is no generic delete-a-line-from-file function, as far as I know.


To remove fist line from a text file

System.IO.StreamReader file = new System.IO.StreamReader(filePath);
string data = file.ReadToEnd();
file.Close();
data = Regex.Replace(data, "<.*\n", "");
System.IO.StreamWriter file = new System.IO.StreamWriter(filePath, false);
file.Write(data);
file.Close();

C# Sharp Exercises: Read the first line from a file, Write a program in C# Sharp to read the first line from a file. Main() { string fileName = @"mytest.txt"; try { // Delete the file if it exists. if (File. Read your file into a Dictionary on non delete lines set the int to 0on line you need to mark as deleted set int to 1. Use a KeyValuePair to extract the lines that don't needed to be deleted and write them to a new file. Dictionary<string, int> output = new Dictionary<string, int>();// read line from file


can do in one line also

File.WriteAllLines(origialFilePath,File.ReadAllLines(originalFilePath).Skip(1));

Assuming you are passing your filePath as parameter to the function.

How to delete the first X lines of a text file using c#, First you load the text file into a string. Then you split it by the line separator into an array of strings. Then write the array to the file line by line, starting at the xth  When all lines have been marked for deletion, the file itself can be deleted, leaving you with about 400 files again. There is no hidden O(n 2) behavior so long as the first file is not closed while the lines are being deleted. But easier still is allow your logging system to keep the 1st and 401st file as is, and remove the 1st file when moving to the 402nd file.


How to Remove a Line From a Text File at Specific Location in C#, csv files we often need to delete the 1st record as it is the header of csv file and is not required. This post describes how to delete a specific line  If you want to remove the first line inside the file, you should use: tail -n +2 "$FILE" > "$FILE.tmp" && mv "$FILE.tmp" "$FILE". The && will make sure that the file doesn't get overwritten when there is a problem. share.


How to delete the first line of a text file?, I'd like to import a text file, delete the first line, and save the remaining lines to a new text file. The first line consists of a single number, while the remaining lines  Essentially, you could read in the contents of your text file into a string, find the beginning of that string, write your information (A,B,C with your carriage returns or line feeds) and then write that information back out into the text file overwriting the original contents and save.


Remove lines from a file, 6 C; 7 C#; 8 C++; 9 Clojure; 10 Common Lisp; 11 D; 12 ECL; 13 Elixir; 14 Erlang; 15 F# if Line_Number < First or else Line_Number > Last then PROC remove lines = ( STRING file name, INT start line, INT number of lines )BOOL: Sometimes, we need to remove a specific line from a text file. For instance, when working with.csv files we often need to delete the 1st record as it is the header of csv file and is not required. This post describes how to delete a specific line from your file. The below code reads myFile.txt file and removes the 1st line from the file.