Delete specific line from a text file?

问题:

I need to delete an exact line from a text file but I cannot for the life of me workout how to go about doing this.

Any suggestions or examples would be greatly appreciated?

Related Questions

Efficient way to delete a line from a text file (C#)

回答1:

If the line you want to delete is based on the content of the line:

string line = null;
string line_to_delete = "the line i want to delete";

using (StreamReader reader = new StreamReader("C:\\input")) {
    using (StreamWriter writer = new StreamWriter("C:\\output")) {
        while ((line = reader.ReadLine()) != null) {
            if (String.Compare(line, line_to_delete) == 0)
                continue;

            writer.WriteLine(line);
        }
    }
}

Or if it is based on line number:

string line = null;
int line_number = 0;
int line_to_delete = 12;

using (StreamReader reader = new StreamReader("C:\\input")) {
    using (StreamWriter writer = new StreamWriter("C:\\output")) {
        while ((line = reader.ReadLine()) != null) {
            line_number++;

            if (line_number == line_to_delete)
                continue;

            writer.WriteLine(line);
        }
    }
}

回答2:

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.

回答3:

One way to do it if the file is not very big is to load all the lines into an array:

string[] lines = File.ReadAllLines("filename.txt");
string[] newLines = RemoveUnnecessaryLine(lines);
File.WriteAllLines("filename.txt", newLines);

回答4:

You can actually use C# generics for this to make it real easy:

        var file = new List<string>(System.IO.File.ReadAllLines("C:\\path"));
        file.RemoveAt(12);
        File.WriteAllLines("C:\\path", file.ToArray());

回答5:

No rocket scien code require .Hope this simple and short code will help.

List linesList = File.ReadAllLines("myFile.txt").ToList();            
linesList.RemoveAt(0);
File.WriteAllLines("myFile.txt"), linesList.ToArray());

OR use this

public void DeleteLinesFromFile(string strLineToDelete)
    {
        string strFilePath = "Provide the path of the text file";
        string strSearchText = strLineToDelete;
        string strOldText;
        string n = "";
        StreamReader sr = File.OpenText(strFilePath);
        while ((strOldText = sr.ReadLine()) != null)
        {
            if (!strOldText.Contains(strSearchText))
            {
                n += strOldText + Environment.NewLine;
            }
        }
        sr.Close();
        File.WriteAllText(strFilePath, n);
    }

回答6:

1. Read and remember each line

2. Identify the one you want to get rid of

3. Forget that one

4. Write the rest back over the top of the file

回答7:

Are you on a Unix operating system?

You can do this with the "sed" stream editor. Read the man page for "sed"

回答8:

This can be done in three steps:

// 1. Read the content of the file
string[] readText = File.ReadAllLines(path);

// 2. Empty the file
File.WriteAllText(path, String.Empty);

// 3. Fill up again, but without the deleted line
using (StreamWriter writer = new StreamWriter(path))
{
    foreach (string s in readText)
    {
        if (!s.Equals(lineToBeRemoved))
        {
            writer.WriteLine(s);
        }
    }
}

回答9:

What? Use file open, seek position then stream erase line using null.

Gotch it? Simple,stream,no array that eat memory,fast.

This work on vb.. Example search line culture=id where culture are namevalue and id are value and we want to change it to culture=en

Fileopen(1, "text.ini")
dim line as string
dim currentpos as long
while true
    line = lineinput(1)
    dim namevalue() as string = split(line, "=")
    if namevalue(0) = "line name value that i want to edit" then
        currentpos = seek(1)
        fileclose()
        dim fs as filestream("test.ini", filemode.open)
        dim sw as streamwriter(fs)
        fs.seek(currentpos, seekorigin.begin)
        sw.write(null)
        sw.write(namevalue + "=" + newvalue)
        sw.close()
        fs.close()
        exit while
    end if
    msgbox("org ternate jua bisa, no line found")
end while

that's all..use #d