Source code for comparefiles.cs

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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Security.Cryptography;
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namespace RobvanderWoude
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{
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	internal class CompareFiles
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	{
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		static string progver = "1.01";
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		static int Main( string[] args )
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		{
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			#region Parse Command Line
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			if ( args.Length < 2 || args.Length > 3 || args.Contains( "/?" ) )

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			{
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				return ShowHelp( );
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			}
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			string file1 = args[0];
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			if ( !File.Exists( file1 ) )
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			{
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				ShowHelp( "File not found: \"{0}\"", file1 );

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				return -2;
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			}
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			string file2 = args[1];
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			if ( !File.Exists( file2 ) )
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			{
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				ShowHelp( "File not found: \"{0}\"", file2 );

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				return -3;
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			}
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			bool ignoretimestamps = false;
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			if ( args.Length == 3 )
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			{
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				if ( args[2].ToUpper( ) == "/IT" )
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				{
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					ignoretimestamps = true;
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				}
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				else
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				{
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					return ShowHelp( "Invalid command line argument \"{0}\"", args[2] );

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				}
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			}
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			#endregion Parse Command Line
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			#region Compare File Sizes
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			long file1size = new FileInfo( file1 ).Length;

			long file2size = new FileInfo( file2 ).Length;

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			if ( file1size > file2size )
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			{
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				Console.WriteLine( "\"{0}\" is bigger", file1 );

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				return 1;
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			}
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			else if ( file1size < file2size )
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			{
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				Console.WriteLine( "\"{0}\" is bigger", file2 );

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				return 2;
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			}
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			else
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			{
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				Console.WriteLine( "File sizes match" );

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			}
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			#endregion Compare File Sizes
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			#region Compare Timestamps
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			DateTime file1timestamp = File.GetLastWriteTime( file1 );

			DateTime file2timestamp = File.GetLastWriteTime( file2 );

			if ( file1timestamp > file2timestamp )

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			{
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				Console.WriteLine( "\"{0}\" is newer", file1 );

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				if ( !ignoretimestamps )
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				{
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					return 3;
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				}
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			}
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			else if ( file1timestamp < file2timestamp )

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			{
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				Console.WriteLine( "\"{0}\" is newer", file2 );

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				if ( !ignoretimestamps )
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				{
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					return 4;
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				}
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			}
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			else
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			{
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				Console.WriteLine( "Timestamps match" );

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			}
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			#endregion Compare Timestamps
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			#region Compare MD5 Checksums
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			string file1md5;
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			string file2md5;
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			using ( var md5 = MD5.Create( ) )
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			{
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				using ( var stream = File.OpenRead( file1 ) )

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				{
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					file1md5 = BitConverter.ToString( md5.ComputeHash( stream ) ).Replace( "-", "" ).ToLowerInvariant( );

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				}
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				using ( var stream = File.OpenRead( file2 ) )

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				{
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					file2md5 = BitConverter.ToString( md5.ComputeHash( stream ) ).Replace( "-", "" ).ToLowerInvariant( );

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				}
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			}
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			if ( file1md5 == file2md5 )
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			{
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				Console.WriteLine( "MD5 checksums match" );

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			}
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			else
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			{
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				Console.WriteLine( "Files have different MD5 checksums" );

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				return 5;
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			}
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			#endregion Compare MD5 Checksums
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			Console.WriteLine( "Files are identical" );

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			return 0;
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		}
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		#region Error handling
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		static int ShowHelp( params string[] errmsg )

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			#region Error Message
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			if ( errmsg.Length > 0 )
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			{
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				List<string> errargs = new List<string>( errmsg );

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				errargs.RemoveAt( 0 );
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				Console.Error.WriteLine( );
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				Console.ForegroundColor = ConsoleColor.Red;

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				Console.Error.Write( "ERROR:\t" );
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				Console.ForegroundColor = ConsoleColor.White;

				Console.Error.WriteLine( errmsg[0], errargs.ToArray( ) );

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				Console.ResetColor( );
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			}
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			#endregion Error Message
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			#region Help Text
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			/*
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			CompareFiles.exe,  Version 1.00
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			Check if two files are identical
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			Usage:        CompareFiles.exe  file1  file2  [ /IT ]

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			Where:        file1 and file2 are the files to compare

			              /IT  Ignore Timestamps (continue even if timestamps differ)

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			Return code:  0    files are identical

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			              1    file1 is bigger
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			              2    file1 is smaller
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			              3    sizes match but file1 is newer

			              4    sizes match but file1 is older

			              5    MD5 checksums are different

			             -1    command line error

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			             -2    file1 not found
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			             -3    file2 not found
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```
			Written by Rob van der Woude
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			https://www.robvanderwoude.com
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			*/
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			#endregion Help Text
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			#region Display Help Text
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			Console.Error.WriteLine( );
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			Console.Error.WriteLine( "CompareFiles.exe,  Version {0}", progver );

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			Console.Error.WriteLine( "Check if two files are identical" );

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			Console.Error.WriteLine( );
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			Console.Error.Write( "Usage:        " );

			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.WriteLine( "CompareFiles.exe  file1  file2  [ /IT ]" );

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			Console.ResetColor( );
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			Console.Error.WriteLine( );
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			Console.Error.Write( "Where:        " );

			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "file1" );
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			Console.ResetColor( );
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			Console.Error.Write( " and " );
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			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "file2" );
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			Console.ResetColor( );
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			Console.Error.WriteLine( " are the files to compare" );

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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.Write( "              /IT  I" );

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			Console.ResetColor( );
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			Console.Error.Write( "gnore " );
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			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "T" );
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			Console.ResetColor( );
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			Console.Error.WriteLine( "imestamps (continue even if timestamps differ)" );

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			Console.Error.WriteLine( );
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			Console.Error.WriteLine( "Return code:  0   files are identical" );

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			Console.Error.WriteLine( "              1   file1 is bigger" );

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			Console.Error.WriteLine( "              2   file1 is smaller" );

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			Console.Error.WriteLine( "              3   sizes match but file1 is newer" );

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			Console.Error.WriteLine( "              4   sizes match but file1 is older" );

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			Console.Error.WriteLine( "              5   MD5 checksums are different" );

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			Console.Error.WriteLine( "             -1   command line error" );

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			Console.Error.WriteLine( "             -2   file1 not found" );

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			Console.Error.WriteLine( "             -3   file2 not found" );

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			Console.Error.WriteLine( );
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			Console.Error.WriteLine( "Written by Rob van der Woude" );

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			Console.Error.WriteLine( "https://www.robvanderwoude.com" );

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			#endregion Display Help Text
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			return -1;
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		}
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		#endregion Error handling
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	}
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}
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