将标头添加到现有文件

Question

How to add text beginning of the existing data in a text file. Basically i need to provide a header before this data in a text file. This header is a dynamic data.

this is my actual text

The claim against the Defendant is for a breach of contract in respect of a Parking Charge Notice issued to the vehicle.

header to add is

17383001 followed by space (1983).

this is my code

FileStream fs = new FileStream(@"C:\Users\IT-Administrator\Desktop\ee.txt", FileMode.Open, FileAccess.Write);
fs.Seek(0, SeekOrigin.Begin);

StreamWriter sw = new StreamWriter(fs);
//sw.WriteLine(comboBox7.Text +comboBox2.Text +textBox6.Text);
sw.WriteLine("{0}{1}{2}{3,-1983}", comboBox7.Text, comboBox2.Text,textBox6.Text, ' ');
sw.Close();
fs.Close();

Answer 1

The simplest is to recreate the whole file:

string header = string.Format("{0}{1}{2}{3,-1983}", comboBox7.Text, comboBox2.Text,textBox6.Text, ' ');
string[] newLines = new[]{ header }.Concat(File.ReadLines(path)).ToArray();
File.WriteAllLines(path, newLines);

Update "i should have blank or empty space of lenght 1983"

Use the string constructor : new string(' ', 1983) , so:

string header = string.Format("{0}{1}{2}{3}"
                 , comboBox7.Text
                 , comboBox2.Text
                 , textBox6.Text
                 , new string(' ', 1983));

Answer 2

The easiest way to achieve what you want is to use File.ReadAllText and File.WriteAllText :

string fileText = File.ReadAllText("C:\\file.txt");
fileText = string.Format("{0}{1}.{2}", "17383001", new string(' ', 1983), fileText);
File.WriteAllText("C:\\file.txt", fileText);