In .NET Framework , the "System.IO.File" class library provides static methods for creating, reading, copying, moving, and deleting files. Here you can find few sample code snippets to Create,Read and Write a Text file in C#.

Create a Text file and Writing data to it in C#

class TextApp
    {
        static void Main(string[] args)
        {
            string fileName = @"F:\Test\Example.txt";

            // create a writer and open the file
            TextWriter tw = new StreamWriter(fileName);
 
            // write a line of text to the file
            tw.WriteLine(DateTime.Now);
 
            // close the stream
            tw.Close();
        }
    }

Read the data from a Textfile in C#

class TextApp
    {
        static void Main(string[] args)
        {
            string fileName = @"F:\Test\Example.txt";

            // create reader & open file
            TextReader tr = new StreamReader(fileName);
 
            // read a line of text
            Console.WriteLine(tr.ReadLine());
 
            // close the stream
            tr.Close();
        }
    }

Different ways to write to a file in C# .NET

string fileName = @"F:\Test\Example.txt";
using (FileStream target = File.Open(fileName , FileMode.Append, FileAccess.Write))
{
    using (StreamWriter writer = new StreamWriter(target))
    {
        writer.WriteLine("Hello world");
    }
}

string fileName = @"F:\Test\Example.txt";
    using (MemoryStream memory = new MemoryStream())
    {
        using (StreamWriter writer = new StreamWriter(memory))
        {
            writer.WriteLine("Hello world from memory");
            writer.Flush();
            using (FileStream fileStream = File.Create(fileName ))
            {
                memory.WriteTo(fileStream);
            }
        }
    }