File And its Operations

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;//It is must require namespace for working with the file and it's operations

namespace File_create
{
    class Program
    {
        static void Main(string[] args)
        {
            string f = @"D:/file2.txt";//You Can create Any type of file at any location
            string m = "Hello World";
            //WriteToFile(f,m);
            ReadAllInfo(f);
            Console.ReadLine();
        }
       
        //Below Function is used to write information to file
        public static void WriteToFile(string file, string msg)
        {
            if (!System.IO.File.Exists(file)) //Check weather file is not there.
            {
                File.Create(file);
                Console.WriteLine("New file is created at location  "+file);
                Console.WriteLine("Enter the Data to File");
                string s=Console.ReadLine();
                using (StreamWriter writer = new StreamWriter(file))
                {
                    writer.WriteLine(msg);
                    writer.WriteLine(s);          
                }
                Console.WriteLine("Data inserted into the file "+file);
            }//End of If
            else
            {
                Console.WriteLine("THE FILE IS ALREADY CREATED.");
                Console.WriteLine("Enter the Data to File");
                string s = Console.ReadLine();
                using (StreamWriter writer = new StreamWriter(file))
                {
                    writer.WriteLine(s);
                    writer.WriteLine(msg);
                }
                Console.WriteLine("Data inserted into the file " + file);
            }//End of else
        }//End of WriteToFile
      
        //Below Function is used to Read Information From the File
        public static void ReadAllInfo(string file)
        {
            if (!File.Exists(file))
            {
                Console.WriteLine("The File Does not Exists.");
            }
            else
            {
                string s = File.ReadAllText(file);
                Console.WriteLine("The File Having Below Information \n"+s);
            }
        }
    }

}

Another Example Find No of Lines Words and Characters of The File And Append it.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace File_create
{
    class Program
    {
        static void Main(string[] args)
        {
            string f = "D:\\file.doc";
            string m = "Hello World";
            WriteToFile(f,m);
            AppendInfo(f);
            ReadAllInfo(f);
            Console.ReadLine();
        }
       
        //Below Function is used to write information to file
        public static void WriteToFile(string file, string msg)
        {
            if (!System.IO.File.Exists(file)) //Check weather file is not there.
            {
                File.Create(file);
                Console.WriteLine("New file is created at location  "+file);
                Console.WriteLine("Enter the Data to File");
                string s=Console.ReadLine();
                StreamWriter writer = new StreamWriter(file);
               
                    writer.WriteLine(msg);
                    writer.WriteLine(s);
                    writer.Close();
               
                Console.WriteLine("Data inserted into the file "+file);
            }//End of If
            else
            {
                Console.WriteLine("THE FILE IS ALREADY CREATED.");
                Console.WriteLine("Enter the Data to File");
                string s = Console.ReadLine();
                StreamWriter writer = new StreamWriter(file);
                writer.WriteLine(msg);
                writer.WriteLine(s);
                writer.Close();
                //using (StreamWriter writer = new StreamWriter(file))
                //{
                //    writer.WriteLine(s);
                //    writer.WriteLine(msg);
                //}
                Console.WriteLine("Data inserted into the file " + file);
            }//End of else
        }//End of WriteToFile
      
        //Below Function is used to Read Information From the File
        public static void ReadAllInfo(string file)
        {
            int w=0, ch=0, l=0;
            if (!File.Exists(file))
            {
                Console.WriteLine("The File Does not Exists.");
            }
            else
            {
                StreamReader reader = File.OpenText(file);
                string s = reader.ReadLine();
                Console.WriteLine("File Found \n\nThe File Having Below Information\n\n" );
                while (s != null)
                {
                   ch = ch + s.Length;
                   l++;
                   for (int i = 0; i < s.Length; i++)
                   {
                       char cha = s[i];
                       if (cha.Equals(' '))
                       {
                           w++;
                       }
                   }
                       Console.WriteLine(s);
                   s=reader.ReadLine();
                }
                w = w + l;
                Console.WriteLine("Lines : "+l);
                Console.WriteLine("Characters :"+ch);
                Console.WriteLine("Words : "+w);
                //string s = File.ReadAllText(file);
                //Console.WriteLine("The File Having Below Information \n"+s);
            }
        }
        public static void AppendInfo(string file)
        {
            if (!File.Exists(file))
            {
                Console.WriteLine("The File Doesn't Exists.");
            }
            else
            {
              StreamWriter writer;
              Console.WriteLine("File Found");
              Console.WriteLine("Enter Text To append");
              string s = Console.ReadLine();
              writer=File.AppendText(file);
              writer.WriteLine(s);
              writer.WriteLine("End OF File");
              writer.Close();               
            }
        }
    }

}


Copy,Delete Files

class Program
    {
        static void Main(string[] args)
        {
            string f = "D:\\file.doc";
            string ff = "D:\\Practice\\file.doc";
            string m = "Hello World";
            //WriteToFile(f,m);
            //AppendInfo(f);
            //ReadAllInfo(f);
            CopyToAnotherLocation(f, ff);
            Console.ReadLine();
        }
        public static void CopyToAnotherLocation(string s,string d)
        {
            File.Delete(d);
            File.Copy(s, d);
            Console.WriteLine("File Copied SuccessFully Completed");
       
        }