Adding header to the output text file correctly, by using streamwriter, C#

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I want to add header to the output text file, after reading and writing with a specified condition.

My code reads from input file and writes to the output file:
Ana Teacher 256
Ben Student 12

i want to add header and output file to be:
User Function Points
Ana Teacher 256
Ben Student 123

I tried to read the file and rewrite it with a new line(header).

What I have tried:

C#

string path2 = path + @"\new.txt";
 string s;
 string header = (User, Function, Points);
 string tempfile = path2 + "\\tempfile.txt"; 
//part of code for stream reader, i am not including here

using (StreamWriter writer = new StreamWriter(path))
            {
                 writer.WriteLine(l);

static void InsertHeader(string path2, string header)
{
    var tempfile = Path.GetTempFileName();
    using (var writer = new StreamWriter(tempfile))
    using (var reader = new StreamReader(path2))
    {
        writer.WriteLine(header);
        while (!reader.EndOfStream)
            writer.WriteLine(reader.ReadLine());
    }
    File.Copy(tempfile, path2, true);
    File.Delete(tempfile);
}

 label2.Text = "File is converted ";

}

Posted 20-Nov-17 1:04am

anabeth4

Updated 20-Nov-17 9:40am

Patrice T

v5

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Tomas Takac 20-Nov-17 7:17am

Why do you need to insert the header into an existing file? Why not write header first and then write data?

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OriginalGriff · Answer 1 · 2017-11-20T01:42:00

Solution 1

You don't define methods inside methods, and you can't open a stream writer on an open file, and you can't overwrite a file that is being read.

As a suggestion, use File.ReadAllText to read your whole file, then add your header text to that, and write it back over the original file:

C#

string path = @"D:\Temp\MyFile.txt";
string data = File.ReadAllText(path);
string withHeader = "The header\n" + data;
File.WriteAllText(withHeader);

Posted 20-Nov-17 1:42am

OriginalGriff

Comments

anabeth4 20-Nov-17 8:25am

hm I understand, thanx a lot.
my question is: if I use File.ReadAllText I think it will change all logic, cause i am printing only those lines of text where points are from 100-300.
Where should i include: File.WriteAllText(withHeader); ?? after writing all lines or not?

OriginalGriff 20-Nov-17 8:40am

Then use ReadAllLines to read the whole file into an array of strings, and build a List of strings to build up the output. Insert your header to the List, and add the lines that are needed to it. Finally, write the List to the file using WriteAllLines:

File.WriteAllLines(path, myList.ToArray());