Write file in C#

    using System;

    using System.IO;

    class FileWrite

    {

        public void WriteData()

        {

            FileStream fs = new FileStream(@"C:\Test Folder\test.txt", FileMode.Open, FileAccess.Write);

            StreamWriter sw = new StreamWriter(fs);

            string str = Console.ReadLine();

            sw.WriteLine(str);

            sw.Flush();

            sw.Close();

            fs.Close();

        }

        public static void Main(String[] args)

        {

            FileWrite fw = new FileWrite();

            fw.WriteData();

            Console.ReadLine();

        }

    }

Read file in C#

    using System;

    using System.IO;

    class FileRead

    {

        public void ReadData()

        {

            FileStream fs = new FileStream(@"C:\Test Folder\test.txt", FileMode.Open, FileAccess.Read);

            StreamReader sr = new StreamReader(fs);

            sr.BaseStream.Seek(0, SeekOrigin.Begin);

            string str = sr.ReadLine();

            while (str != null)

            {

                Console.WriteLine("{0}", str);

                str = sr.ReadLine();

            }

            sr.Close();

            fs.Close();

        }

        public static void Main(String[] args)

        {

            FileRead fr = new FileRead();

            fr.ReadData();

            Console.ReadLine();

        }

    }

OR

    using System;

    using System.IO;

    class FileRead

    {

        public void ReadData()

        {

            FileStream fs = new FileStream(@"C:\Test Folder\test.txt", FileMode.Open, FileAccess.Read);

            StreamReader sr = new StreamReader(fs);

            sr.BaseStream.Seek(0, SeekOrigin.Begin);

            string str = sr.ReadToEnd();

            Console.WriteLine("{0}", str);

            sr.Close();

            fs.Close();

        }

        public static void Main(String[] args)

        {

            FileRead fr = new FileRead();

            fr.ReadData();

 Console.ReadLine();

        }

    }

Check leap year in c#

    class LeapYear

    {

        public static void Main(string[] args)

        {

            int Year;

            Console.WriteLine("Enter the Year: ");

            Year = Convert.ToInt32(Console.ReadLine());

            if ((Year % 4 == 0) && (Year % 100 != 0 || Year % 400 == 0))

            {

                Console.WriteLine("The Year you have entered is a LeapYear: {0}", Year);

            }

            else

            {

                Console.WriteLine("The Year you have entered is not a Leap Year: {0}", Year);

            }

            Console.ReadLine();

        }

    }

Delete file in c#

using System.IO;

Delete respective file

string fileName = "test.txt";

string sourcePath = @"C:\Test Folder";

string sourceFile = Path.Combine(sourcePath, fileName);

if (File.Exists(sourceFile))

{

    File.Delete(sourceFile);

}

Delete all files

string sourcePath = @"C:\Test Folder";

string[] sourcefiles = Directory.GetFiles(sourcePath);

foreach (string sourcefile in sourcefiles)

{

    File.Delete(sourcefile);

}

Delete only .txt extension files

string sourcePath = @"C:\Test Folder";

string[] sourcefiles = Directory.GetFiles(sourcePath);

foreach (string sourcefile in sourcefiles)

{

    string ext = Path.GetExtension(sourcefile);

    if (ext.Equals(".txt"))

    {

        File.Delete(sourcefile);

    }

}

Move file from one folder to another in c#

using System.IO;

Move file from Root Folder to Sub Folder

string fileName = "test.txt";

string sourcePath = @"C:\Test Folder";

string targetPath = @"C:\Test Folder\Sub Folder";

string sourceFile = Path.Combine(sourcePath, fileName);

string destFile = Path.Combine(targetPath, fileName);

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

File.Move(sourceFile, destFile);    

Move file from one folder to another folder

string fileName = "test.txt";

string sourcePath = @"C:\Source Folder";

string targetPath = @"C:\Destination Folder";

string sourceFile = Path.Combine(sourcePath, fileName);

string destFile = Path.Combine(targetPath, fileName);

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

File.Move(sourceFile, destFile);    

Move file from one directories to another directories

string fileName = "test.txt";

string sourcePath = @"C:\Source Folder";

string targetPath = @"D:\Destination Folder";

string sourceFile = Path.Combine(sourcePath, fileName);

string destFile = Path.Combine(targetPath, fileName);

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

File.Move(sourceFile, destFile);    

Move all files from Root Folder to Sub Folder

string sourcePath = @"C:\Test Folder";

string targetPath = @"C:\Test Folder\Sub Folder";

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

string[] sourcefiles = Directory.GetFiles(sourcePath);

foreach (string sourcefile in sourcefiles)

{

    string fileName = Path.GetFileName(sourcefile);

    string destFile = Path.Combine(targetPath, fileName);

    File.Move(sourcefile, destFile);

}

Move all files from one folder to another folder

string sourcePath = @"C:\Source Folder";

string targetPath = @"C:\Destination Folder";

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

string[] sourcefiles = Directory.GetFiles(sourcePath);

foreach (string sourcefile in sourcefiles)

{

    string fileName = Path.GetFileName(sourcefile);

    string destFile = Path.Combine(targetPath, fileName);

    File.Move(sourcefile, destFile);

}

Move all files from one directories to another directories

string sourcePath = @"C:\Source Folder";

string targetPath = @"D:\Destination Folder";

if (!Directory.Exists(targetPath))

{

    Directory.CreateDirectory(targetPath);

}

string[] sourcefiles = Directory.GetFiles(sourcePath);

foreach (string sourcefile in sourcefiles)

{

    string fileName = Path.GetFileName(sourcefile);

    string destFile = Path.Combine(targetPath, fileName);

    File.Move(sourcefile, destFile);

}

Note:-

While moving files, if file already exists in destination folder. It’s throw error.