[c#] How to Save Console.WriteLine Output to Text File

I have a program which outputs various results onto a command line console.

How do I save the output to a text file using a StreamReader or other techniques?

System.Collections.Generic.IEnumerable<String> lines = File.ReadAllLines(@"C:\Test\ntfs8.txt");

foreach (String r in lines.Skip(1))
{
    String[] token = r.Split(',');
    String[] datetime = token[0].Split(' ');
    String timeText = datetime[4];
    String actions = token[2];
    Console.WriteLine("The time for this array is: " + timeText);
    Console.WriteLine(token[7]);
    Console.WriteLine(actions);
    MacActions(actions);
    x = 1;
    Console.WriteLine("================================================");
}

if (x == 2)
{
    Console.WriteLine("The selected time does not exist within the log files!");
}

System.IO.StreamReader reader = ;
string sRes = reader.ReadToEnd();
StreamWriter SW;
SW = File.CreateText("C:\\temp\\test.bodyfile");
SW.WriteLine(sRes);
SW.Close();
Console.WriteLine("File Created");
reader.Close();

This question is related to c#

The answer is


Try if this works:

FileStream filestream = new FileStream("out.txt", FileMode.Create);
var streamwriter = new StreamWriter(filestream);
streamwriter.AutoFlush = true;
Console.SetOut(streamwriter);
Console.SetError(streamwriter);

Based in the answer by WhoIsNinja:

This code will output both into the Console and into a Log string that can be saved into a file, either by appending lines to it or by overwriting it.

The default name for the log file is 'Log.txt' and is saved under the Application path.

public static class Logger
{
    public static StringBuilder LogString = new StringBuilder();
    public static void WriteLine(string str)
    {
        Console.WriteLine(str);
        LogString.Append(str).Append(Environment.NewLine);
    }
    public static void Write(string str)
    {
        Console.Write(str);
        LogString.Append(str);

    }
    public static void SaveLog(bool Append = false, string Path = "./Log.txt")
    {
        if (LogString != null && LogString.Length > 0)
        {
            if (Append)
            {
                using (StreamWriter file = System.IO.File.AppendText(Path))
                {
                    file.Write(LogString.ToString());
                    file.Close();
                    file.Dispose();
                }
            }
            else
            {
                using (System.IO.StreamWriter file = new System.IO.StreamWriter(Path))
                {
                    file.Write(LogString.ToString());
                    file.Close();
                    file.Dispose();
                }
            }               
        }
    }
}

Then you can use it like this:

Logger.WriteLine("==========================================================");
Logger.Write("Loading 'AttendPunch'".PadRight(35, '.'));
Logger.WriteLine("OK.");

Logger.SaveLog(true); //<- default 'false', 'true' Append the log to an existing file.

Necromancing.
I usually just create a class, which I can wrap around main in an IDisposable.
So I can log the console output to a file without modifying the rest of the code.
That way, I have the output in both the console and for later reference in a text-file.

public class Program
{

    public static async System.Threading.Tasks.Task Main(string[] args)
    {
        using (ConsoleOutputMultiplexer co = new ConsoleOutputMultiplexer())
        {
            // Do something here
            System.Console.WriteLine("Hello Logfile and Console 1 !");
            System.Console.WriteLine("Hello Logfile and Console 2 !");
            System.Console.WriteLine("Hello Logfile and Console 3 !");
        } // End Using co 


        System.Console.WriteLine(" --- Press any key to continue --- ");
        System.Console.ReadKey();

        await System.Threading.Tasks.Task.CompletedTask;
    } // End Task Main 

}

with

public class MultiTextWriter
    : System.IO.TextWriter
{

    protected System.Text.Encoding m_encoding;
    protected System.Collections.Generic.IEnumerable<System.IO.TextWriter> m_writers;


    public override System.Text.Encoding Encoding => this.m_encoding;


    public override System.IFormatProvider FormatProvider
    {
        get
        {
            return base.FormatProvider;
        }
    }


    public MultiTextWriter(System.Collections.Generic.IEnumerable<System.IO.TextWriter> textWriters, System.Text.Encoding encoding)
    {
        this.m_writers = textWriters;
        this.m_encoding = encoding;
    }


    public MultiTextWriter(System.Collections.Generic.IEnumerable<System.IO.TextWriter> textWriters)
        : this(textWriters, textWriters.GetEnumerator().Current.Encoding)
    { }


    public MultiTextWriter(System.Text.Encoding enc, params System.IO.TextWriter[] textWriters)
        : this((System.Collections.Generic.IEnumerable<System.IO.TextWriter>)textWriters, enc)
    { }


    public MultiTextWriter(params System.IO.TextWriter[] textWriters)
        : this((System.Collections.Generic.IEnumerable<System.IO.TextWriter>)textWriters)
    { }


    public override void Flush()
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            thisWriter.Flush();
        }
    }

    public async override System.Threading.Tasks.Task FlushAsync()
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            await thisWriter.FlushAsync();
        }

        await System.Threading.Tasks.Task.CompletedTask;
    }


    public override void Write(char[] buffer, int index, int count)
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            thisWriter.Write(buffer, index, count);
        }
    }


    public override void Write(System.ReadOnlySpan<char> buffer)
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            thisWriter.Write(buffer);
        }
    }


    public async override System.Threading.Tasks.Task WriteAsync(char[] buffer, int index, int count)
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            await thisWriter.WriteAsync(buffer, index, count);
        }

        await System.Threading.Tasks.Task.CompletedTask;
    }


    public async override System.Threading.Tasks.Task WriteAsync(System.ReadOnlyMemory<char> buffer, System.Threading.CancellationToken cancellationToken = default)
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            await thisWriter.WriteAsync(buffer, cancellationToken);
        }

        await System.Threading.Tasks.Task.CompletedTask;
    }


    protected override void Dispose(bool disposing)
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            thisWriter.Dispose();
        }
    }


    public async override System.Threading.Tasks.ValueTask DisposeAsync()
    {
        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            await thisWriter.DisposeAsync();
        }

        await System.Threading.Tasks.Task.CompletedTask;
    }

    public override void Close()
    {

        foreach (System.IO.TextWriter thisWriter in this.m_writers)
        {
            thisWriter.Close();
        }
        
    } // End Sub Close 


} // End Class MultiTextWriter 



public class ConsoleOutputMultiplexer
    : System.IDisposable
{

    protected System.IO.TextWriter m_oldOut;
    protected System.IO.FileStream m_logStream;
    protected System.IO.StreamWriter m_logWriter;

    protected MultiTextWriter m_multiPlexer;


    public ConsoleOutputMultiplexer()
    {
        this.m_oldOut = System.Console.Out;

        try
        {
            this.m_logStream = new System.IO.FileStream("./Redirect.txt", System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Write);
            this.m_logWriter = new System.IO.StreamWriter(this.m_logStream);
            this.m_multiPlexer = new MultiTextWriter(this.m_oldOut.Encoding, this.m_oldOut, this.m_logWriter);

            System.Console.SetOut(this.m_multiPlexer);
        }
        catch (System.Exception e)
        {
            System.Console.WriteLine("Cannot open Redirect.txt for writing");
            System.Console.WriteLine(e.Message);
            return;
        }

    } // End Constructor 


    void System.IDisposable.Dispose()
    {
        System.Console.SetOut(this.m_oldOut);

        if (this.m_multiPlexer != null)
        {
            this.m_multiPlexer.Flush();
            if (this.m_logStream != null)
                this.m_logStream.Flush();

            this.m_multiPlexer.Close();
        }
        
        if(this.m_logStream != null)
            this.m_logStream.Close();
    } // End Sub Dispose 


} // End Class ConsoleOutputMultiplexer 

For the question:

How to save Console.Writeline Outputs to text file?

I would use Console.SetOut as others have mentioned.


However, it looks more like you are keeping track of your program flow. I would consider using Debug or Trace for keeping track of the program state.

It works similar the console except you have more control over your input such as WriteLineIf.

Debug will only operate when in debug mode where as Trace will operate in both debug or release mode.

They both allow for listeners such as output files or the console.

TextWriterTraceListener tr1 = new TextWriterTraceListener(System.Console.Out);
Debug.Listeners.Add(tr1);

TextWriterTraceListener tr2 = new TextWriterTraceListener(System.IO.File.CreateText("Output.txt"));
Debug.Listeners.Add(tr2);

-http://support.microsoft.com/kb/815788


do you want to write code for that or just use command-line feature 'command redirection' as follows:

app.exe >> output.txt

as demonstrated here: http://discomoose.org/2006/05/01/output-redirection-to-a-file-from-the-windows-command-line/ (Archived at archive.org)

EDIT: link dead, here's another example: http://pcsupport.about.com/od/commandlinereference/a/redirect-command-output-to-file.htm


Using only configuration in your app.config:

    <system.diagnostics> 
        <trace autoflush="true" indentsize="4"> 
              <listeners> 

              <add name="consoleListener" type="System.Diagnostics.ConsoleTraceListener"/>

            <!--
            <add name="logListener" type="System.Diagnostics.TextWriterTraceListener" initializeData="TextWriterOutput.log" /> 
            <add name="EventLogListener" type="System.Diagnostics.EventLogTraceListener" initializeData="MyEventLog"/>
             -->

             <!--
              Remove the Default listener to avoid duplicate messages
              being sent to the debugger for display
             -->
             <remove name="Default" />

             </listeners> 
        </trace> 
  </system.diagnostics>

For testing, you can use DebugView before running the program, then we can easily view all of the log messages.

References:
http://blogs.msdn.com/b/jjameson/archive/2009/06/18/configuring-logging-in-a-console-application.aspx http://www.thejoyofcode.com/from_zero_to_logging_with_system_diagnostics_in_15_minutes.aspx
Redirect Trace output to Console
Problem redirecting debug output to a file using trace listener
https://ukadcdiagnostics.codeplex.com/
http://geekswithblogs.net/theunstablemind/archive/2009/09/09/adventures-in-system.diagnostics.aspx


Create a class Logger(code below), replace Console.WriteLine with Logger.Out. At the end write to a file the string Log

public static class Logger
{        
     public static StringBuilder LogString = new StringBuilder(); 
     public static void Out(string str)
     {
         Console.WriteLine(str);
         LogString.Append(str).Append(Environment.NewLine);
     }
 }

Use Console.SetOut to redirect to a TextWriter as described here: http://msdn.microsoft.com/en-us/library/system.console.setout.aspx