Source code for countdown.cs

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using System;
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using System.Collections.Generic;
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using System.Threading;
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using System.Text.RegularExpressions;
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namespace RobvanderWoude
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{
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	class CountDown
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	{
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		static readonly string progver = "2.01";

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		static int Main( string[] args )
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		{
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			string prefix = string.Empty;
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			string suffix = string.Empty;
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			bool returnremaining = false;
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			int seconds = 0;
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			#region Parse Command Line
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			if ( args.Length == 0 )
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			{
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				return ShowHelp( );
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			}
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			foreach ( string arg in args )
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			{
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				if ( arg == "/?" )
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				{
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					return ShowHelp( );
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				}
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				else if ( arg.ToUpper( ) == "/R" )
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				{
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					if ( returnremaining )
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					{
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						return ShowHelp( "Duplicate command line switch /R" );

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					}
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					returnremaining = true;
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				}
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				else if ( int.TryParse( arg, out int test ) )

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				{
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					if ( seconds == 0 )
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					{
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						seconds = test;
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					}
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					else
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					{
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						return ShowHelp( "Duplicate timeout argument" );

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					}
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				}
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				else if ( string.IsNullOrWhiteSpace( prefix ) )

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				{
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					prefix = arg;
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				}
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				else if ( string.IsNullOrWhiteSpace( suffix ) )

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				{
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					suffix = arg;
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				}
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				else
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				{
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					return ShowHelp( "Invalid or too many command line arguments", arg );

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				}
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			}
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			// Enable single command line argument for prefix seconds suffix

			if ( seconds == 0 && !string.IsNullOrWhiteSpace( prefix ) && string.IsNullOrWhiteSpace( suffix ) )

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			{
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				string pattern = @"^([^\d]*)(\d+)(.*)$";

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				Regex regex = new Regex( pattern );
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				if ( regex.IsMatch( prefix ) )
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				{
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					MatchCollection matches = regex.Matches( prefix );

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					if ( matches.Count == 1 )
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					{
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						if ( matches[0].Groups.Count == 4 )

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						{
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							if ( int.TryParse( matches[0].Groups[2].ToString( ), out seconds ) )

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							{
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								prefix = matches[0].Groups[1].ToString( );

								suffix = matches[0].Groups[3].ToString( );

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							}
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						}
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					}
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				}
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			}
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			if ( seconds < 1 || seconds > 86400 )

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			{
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				return ShowHelp( "Specified timeout ({0}) outside allowed range", seconds.ToString( ) );

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			}
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			#endregion Parse Command Line
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			// Temporarily change console properties

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			Console.CursorVisible = false;
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			Console.TreatControlCAsInput = true;
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			// Determine the string length for number of digits

			int counterlength = seconds.ToString( ).Length;

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			// Determine the prefix string length

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			int prefixlength = prefix.Length;
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			// Determine the suffix string length

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			int suffixlength = suffix.Length;
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			// Display optional message
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			Console.Write( prefix );
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			// Clear space on screen for countdown counter value

			Console.Write( new String( ' ', counterlength + suffixlength ) );

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			// Start countdown
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			int countdown = seconds;
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			while ( !Console.KeyAvailable && countdown > 0 )

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			{
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				// Wipe previous countdown counter value from screen

				Console.Write( new String( '\b', counterlength + suffixlength ) );

				Console.Write( new String( ' ', counterlength + suffixlength ) );

				Console.Write( new String( '\b', counterlength + suffixlength ) );

				Console.Write( "{0," + counterlength + "}", countdown );

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				Console.Write( suffix );
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				countdown -= 1; // decrement countdown counter

				Thread.Sleep( 1000 ); // wait 1 second

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			}
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			// Wipe entire countdown counter line from screen

			Console.Write( new String( '\b', counterlength + suffixlength + prefixlength ) );

			Console.Write( new String( ' ', counterlength + suffixlength + prefixlength ) );

			Console.Write( new String( '\b', counterlength + suffixlength + prefixlength ) );

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			// Restore console properties
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			Console.CursorVisible = true;
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			Console.TreatControlCAsInput = false;

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			// If a key is pressed to interrupt countdown, remove it from keyboard buffer

			if ( countdown > 0 && Console.KeyAvailable )

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			{
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				Console.ReadKey( true );
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			}
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			// Return code depends on command line switch and on countdown completion

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			if ( returnremaining )
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			{
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				return countdown; // remaining number of seconds (requires /R)

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			}
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			else if ( countdown == 0 )
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			{
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				return 0; // countdown completed
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			}
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			else
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			{
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				return 2; // countdown interrupted (not with /R)

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			}
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		}
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		static int ShowHelp( params string[] errmsg )

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		{
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			#region Help Text
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			/*
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			CountDown,  Version 2.01
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			Count down for the specified number of seconds or until a key is pressed

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```

			Usage:  COUNTDOWN  [ prefix ]  seconds  [ suffix ]  [ /R ]

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```

			   or:  COUNTDOWN  "prefix seconds suffix"  [ /R ]

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```

			Where:  prefix     optional prefix message for the counter, e.g. "Waiting "

			        seconds    delay in seconds (1 .. 86400 = 1 second .. 24 hours)

			        suffix     optional suffix message for the counter, e.g. " seconds"

			        /R         return code equals the number of Remaining seconds

			                   (default: return code 0 = OK, 1 = errors, 2 = key pressed)

```
 
```

			Note:   COUNTDOWN "Wait " 20 " seconds" is equal to COUNTDOWN "Wait 20 seconds"

			        In the latter notation the first number on the command line will be

			        used for seconds, any following number will be included in suffix.

```
 
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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 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 Display Help Text
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			Console.Error.WriteLine( );
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			Console.Error.WriteLine( "CountDown,  Version {0}", progver );

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			Console.Error.WriteLine( "Count down for the specified number of seconds or until a key is pressed" );

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			Console.Error.WriteLine( );
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			Console.Error.Write( "Usage:  " );
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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.WriteLine( "COUNTDOWN  [ prefix ]  seconds  [ suffix ]  [ /R ]" );

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			Console.ResetColor( );
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			Console.Error.WriteLine( );
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			Console.Error.Write( "   or:  " );
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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.WriteLine( "COUNTDOWN  \"prefix seconds suffix\"  [ /R ]" );

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			Console.ResetColor( );
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			Console.Error.WriteLine( );
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			Console.Error.Write( "Where:  " );
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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.Write( "prefix     " );

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			Console.ResetColor( );
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			Console.Error.WriteLine( "optional prefix message for the counter, e.g. \"Waiting \"" );

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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.Write( "        seconds    " );

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			Console.ResetColor( );
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			Console.Error.WriteLine( "delay in seconds (1 .. 86400 = 1 second .. 24 hours)" );

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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.Write( "        suffix     " );

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			Console.ResetColor( );
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			Console.Error.WriteLine( "optional suffix message for the counter, e.g. \" seconds\"" );

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			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "        /R" );
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			Console.ResetColor( );
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			Console.Error.Write( "         return code equals the number of " );

			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "R" );
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			Console.ResetColor( );
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			Console.Error.WriteLine( "emaining seconds" );

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			Console.Error.WriteLine( "                   (default: return code 0 = OK, 1 = errors, 2 = key pressed)" );

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			Console.Error.WriteLine( );
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			Console.Error.Write( "Note:   " );
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			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.Write( "COUNTDOWN \"Wait \" 20 \" seconds\" " );

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			Console.ResetColor( );
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			Console.Error.Write( "is equal to " );

			Console.ForegroundColor = ConsoleColor.White;

			Console.Error.WriteLine( "COUNTDOWN \"Wait 20 seconds\"" );

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			Console.ResetColor( );
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			Console.Error.WriteLine( "        In the latter notation the first number on the command line will be" );

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			Console.Error.Write( "        used for " );

			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "seconds" );
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			Console.ResetColor( );
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			Console.Error.Write( ", any following number will be included in " );

			Console.ForegroundColor = ConsoleColor.White;

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			Console.Error.Write( "suffix" );
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			Console.ResetColor( );
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			Console.Error.WriteLine( "." );
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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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	}
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}
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