How can I update the current line in a C Windows Console App

Question

When building a Windows Console App in C   is it possible to write to the console without having to extend a current line or go to a new line   For example  if I want to show a percentage representing how close a process is to completion  I d just like to update the value on the same line as the cursor  and not have to put each percentage on a new line   Can this be done with a  standard  C  console app

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The SetCursorPosition method works in multi-threading scenario  where the other two methods don t

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Inspired by  E Lahu Solution  implementation of a bar progress with percentage   public class ConsoleSpinner       private int  counter       public void Turn Color color  int max  string prefix    Completed   string symbol        int position   0                Console SetCursorPosition 0  position           Console Write    prefix   ComputeSpinner  counter  max  symbol     color            counter    counter    max   0    counter   1             public string ComputeSpinner int nmb  int max  string symbol                var spinner   new StringBuilder            if  nmb    0              return   r             spinner Append     nmb                 for  var i   0  i  lt  max  i                          spinner Append i  lt  nmb   symbol                            spinner Append               return spinner ToString              public static void Main string   args                var progressBar  new ConsoleSpinner            for  int i   0  i  lt  1000  i                          progressBar Turn Color Aqua 100               Thread Sleep 1000

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Explicitly using a Carrage Return   r  at the beginning of the line rather than  implicitly or explicitly  using a New Line   n  at the end should get what you want   For example   void demoPercentDone         for int i   0  i  lt  100  i              System Console Write    rProcessing  0        i            System Threading Thread Sleep  1000              System Console WriteLine

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So far we have three competing alternatives for how to do this   Console Write   r 0       value                           Option 1  carriage return Console Write   b b b b b 0    value                      Option 2  backspace                                                           Option 3 in two parts      Console SetCursorPosition 0  Console CursorTop        - Move cursor     Console Write value                                   - Rewrite     I ve always used Console CursorLeft   0  a variation on the third option  so I decided to do some tests   Here s the code I used   public static void CursorTest         int testsize   1000000       Console WriteLine  Testing cursor position        Stopwatch sw   new Stopwatch        sw Start        for  int i   0  i  lt  testsize  i                  Console Write   rCounting   0         i             sw Stop        Console WriteLine   nTime using   r   0    sw ElapsedMilliseconds        sw Reset        sw Start        int top   Console CursorTop      for  int i   0  i  lt  testsize  i                  Console SetCursorPosition 0  top                   Console Write  Counting   0         i             sw Stop        Console WriteLine   nTime using CursorLeft   0    sw ElapsedMilliseconds        sw Reset        sw Start        Console Write  Counting                   for  int i   0  i  lt  testsize  i                          Console Write   b b b b b b b b 0 8    i              sw Stop        Console WriteLine   nTime using   b   0    sw ElapsedMilliseconds       On my machine  I get the following results    Backspaces  25 0 seconds Carriage Returns  28 7 seconds SetCursorPosition  49 7 seconds   Additionally  SetCursorPosition caused noticeable flicker that I didn t observe with either of the alternatives   So  the moral is to use backspaces or carriage returns when possible  and thanks for teaching me a faster way to do this  SO     Update  In the comments  Joel suggests that SetCursorPosition is constant with respect to the distance moved while the other methods are linear   Further testing confirms that this is the case  however constant time and slow is still slow   In my tests  writing a long string of backspaces to the console is faster than SetCursorPosition until somewhere around 60 characters   So backspace is faster for replacing portions of the line shorter than 60 characters  or so   and it doesn t flicker  so I m going to stand by my initial endorsement of  b over  r and SetCursorPosition

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i was looking for same solution in vb net and i found this one and it s great    however as  JohnOdom suggested a better way to handle the blanks space if previous one is larger than current one    i make a function in vb net and thought someone could get helped      here is my code   Private Sub sPrintStatus strTextToPrint As String  Optional boolIsNewLine As Boolean   False      REM intLastLength is declared as public variable on global scope like below     REM intLastLength As Integer     If boolIsNewLine   True Then         intLastLength   0     End If     If intLastLength  gt  strTextToPrint Length Then         Console Write Convert ToChar 13   amp  strTextToPrint PadRight strTextToPrint Length    intLastLength - strTextToPrint Length   Convert ToChar            Else         Console Write Convert ToChar 13   amp  strTextToPrint      End If     intLastLength   strTextToPrint Length End Sub

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If you want update one line  but the information is too long to show on one line  it may need some new lines  I ve encountered this problem  and below is one way to solve this   public class DumpOutPutInforInSameLine          content show in how many lines     int TotalLine   0         start cursor line     int cursorTop   0          use to set  character number show in one line     int OneLineCharNum   75       public void DumpInformation string content                OutPutInSameLine content           SetBackSpace               static void backspace int n                for  var i   0  i  lt  n    i              Console Write   b  b               public  void SetBackSpace                  if  TotalLine    0                        backspace OneLineCharNum                     else                       TotalLine--              while  TotalLine  gt   0                                backspace OneLineCharNum                   TotalLine--                  if  TotalLine  gt   0                                        Console SetCursorPosition OneLineCharNum  cursorTop   TotalLine                                                         private void OutPutInSameLine string content                  Console WriteLine TotalNum            cursorTop   Console CursorTop           TotalLine   content Length   OneLineCharNum           if  content Length   OneLineCharNum  gt  0                        TotalLine                        if  TotalLine    0                        Console Write   0    content                return                      int i   0          while  i  lt  TotalLine                        int cNum   i   OneLineCharNum              if  i  lt  TotalLine - 1                                Console WriteLine   0    content Substring cNum  OneLineCharNum                              else                               Console Write   0    content Substring cNum  content Length - cNum                              i                        class Program       static void Main string   args                 DumpOutPutInforInSameLine outPutInSameLine   new DumpOutPutInforInSameLine             outPutInSameLine DumpInformation              outPutInSameLine DumpInformation  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb              outPutInSameLine DumpInformation  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa            outPutInSameLine DumpInformation  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb               need several lines         outPutInSameLine DumpInformation  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa            outPutInSameLine DumpInformation  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb             outPutInSameLine DumpInformation  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa            outPutInSameLine DumpInformation  bbbbbbbbbbbbbbbbbbbbbbbbbbb

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I just had to play with the divo s ConsoleSpinner class   Mine is nowhere near as concise  but it just didn t sit well with me that users of that class have to write their own while true  loop   I m shooting for an experience more like this   static void Main string   args        Console Write  Working            ConsoleSpinner spin   new ConsoleSpinner        spin Start            Do some work         spin Stop         And I realized it with the code below   Since I don t want my Start   method to block  I don t want the user to have to worry about writing a while spinFlag  -like loop  and I want to allow multiple spinners at the same time I had to spawn a separate thread to handle the spinning   And that means the code has to be a lot more complicated     Also  I haven t done that much multi-threading so it s possible  likely even  that I ve left a subtle bug or three in there   But it seems to work pretty well so far   public class ConsoleSpinner   IDisposable              public ConsoleSpinner                 CursorLeft   Console CursorLeft          CursorTop   Console CursorTop               public ConsoleSpinner bool start            this                 if  start  Start               public void Start                    prevent two conflicting Start   calls ot the same instance         lock  instanceLocker                         if   running                                 running   true                  turner   new Thread Turn                   turner Start                                       public void StartHere                 SetPosition            Start               public void Stop                 lock  instanceLocker                        if   running  return               running   false              if    turner Join 250                   turner Abort                         public void SetPosition                 SetPosition Console CursorLeft  Console CursorTop              public void SetPosition int left  int top                bool wasRunning            prevent other start stops during move         lock  instanceLocker                        wasRunning   running              Stop                 CursorLeft   left              CursorTop   top               if  wasRunning  Start                          public bool IsSpinning   get   return running             ---  PRIVATE ---         private int counter -1      private Thread turner       private bool running   false      private int rate   100      private int CursorLeft      private int CursorTop      private Object instanceLocker   new Object        private static Object console   new Object         private void Turn                 while  running                        counter                    prevent two instances from overlapping cursor position updates                weird things can still happen if the main ui thread moves the cursor during an update and context switch             lock  console                                                  int OldLeft   Console CursorLeft                  int OldTop   Console CursorTop                  Console SetCursorPosition CursorLeft  CursorTop                    switch  counter                                        case 0  Console Write       break                      case 1  Console Write  -    break                      case 2  Console Write        break                      case 3  Console Write       counter   -1  break                                    Console SetCursorPosition OldLeft  OldTop                              Thread Sleep rate                     lock  console                 clean up             int OldLeft   Console CursorLeft              int OldTop   Console CursorTop              Console SetCursorPosition CursorLeft  CursorTop               Console Write                   Console SetCursorPosition OldLeft  OldTop                        public void Dispose                 Stop

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If you print only   r  to the console the cursor goes back to the beginning of the current line and then you can rewrite it  This should do the trick   for int i   0  i  lt  100    i        Console Write   r 0        i       Notice the few spaces after the number to make sure that whatever was there before is erased  Also notice the use of Write   instead of WriteLine   since you don t want to add an   n  at the end of the line

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You can use the  b  backspace  escape sequence to backup a particular number of characters on the current line  This just moves the current location  it does not remove the characters   For example   string line      for int i 0  i lt 100  i          string backup new string   b  line Length       Console Write backup       line string Format   0    i       Console Write line       Here  line is the percentage line to write to the console  The trick is to generate the correct number of  b characters for the previous output   The advantage of this over the  r approach is that if works even if your percentage output is not at the beginning of the line

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From the Console docs in MSDN      You can solve this problem by setting   the TextWriter NewLine property of the   Out or Error property to another line   termination string  For example  the   C  statement  Console Error NewLine       r n r n    sets the line termination   string for the standard error output   stream to two carriage return and line   feed sequences  Then you can   explicitly call the WriteLine method   of the error output stream object  as   in the C  statement    Console Error WriteLine      So - I did this     Console Out Newline   String Empty    Then I am able to control the output myself   Console WriteLine  Starting item 1         Item1    Console WriteLine  OK  nStarting Item2       Another way of getting there

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Here is my take on s soosh s and 0xA3 s answers  It can update the console with user messages while updating the spinner and has an elapsed time indicator aswell   public class ConsoleSpiner   IDisposable       private static readonly string INDICATOR     -          private static readonly string MASK     r 0   1 c   2        int counter      Timer timer      string message       public ConsoleSpiner             counter   0          timer   new Timer 200           timer Elapsed    TimerTick             public void Start             timer Start               public void Stop             timer Stop            counter   0             public string Message           get   return message            set   message   value               private void TimerTick object sender  ElapsedEventArgs e            Turn               private void Turn             counter            var elapsed   TimeSpan FromMilliseconds counter   200           Console Write MASK  INDICATOR counter   4   elapsed  this Message              public void Dispose             Stop            timer Elapsed -  TimerTick          this timer Dispose              usage is something like this   class Program       static void Main string   args                using  var spinner   new ConsoleSpiner                          spinner Start                spinner Message    About to do some heavy staff  -               DoWork                spinner Message    Now processing other staff               OtherWork                spinner Stop                      Console WriteLine  COMPLETED      nPress any key to exit

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r is used for these scenarios   r represents a carriage return which means the cursor returns to the start of the line  That s why Windows uses  n r as its new line marker   n moves you down a line  and  r returns you to the start of the line

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public void Update string data                Console Write string Format   r 0       PadLeft Console CursorLeft                  Console Write string Format   r 0    data

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You can use Console SetCursorPosition to set the position of the cursor and then write at the current position   Here is an example showing a simple  spinner    static void Main string   args        var spin   new ConsoleSpinner        Console Write  Working            while  true                 spin Turn             public class ConsoleSpinner       int counter       public void Turn                 counter                    switch  counter   4                        case 0  Console Write       counter   0  break              case 1  Console Write  -    break              case 2  Console Write        break              case 3  Console Write       break                    Thread Sleep 100           Console SetCursorPosition Console CursorLeft - 1  Console CursorTop             Note that you will have to make sure to overwrite any existing output with new output or blanks   Update  As it has been criticized that the example moves the cursor only back by one character  I will add this for clarification  Using SetCursorPosition you may set the cursor to any position in the console window    Console SetCursorPosition 0  Console CursorTop     will set the cursor to the beginning of the current line  or you can use Console CursorLeft   0 directly

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I was doing a search for this to see if the solution I wrote could be optimised for speed  What I wanted was a countdown timer  not just updating the current line  Here s what I came up with  Might be useful to someone              int sleepTime   5   60        5 minutes              for  int secondsRemaining   sleepTime  secondsRemaining  gt  0  secondsRemaining --                                double minutesPrecise   secondsRemaining   60                  double minutesRounded   Math Round minutesPrecise  0                   int seconds   Convert ToInt32  minutesRounded   60  - secondsRemaining                   Console Write    rProcess will resume in  minutesRounded   String Format   0 D2    -seconds                       Thread Sleep 1000                             Console WriteLine

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Here s another one  D  class Program       static void Main string   args                Console Write  Working                int spinIndex   0          while  true                           obfuscate FTW  Let s hope overflow is disabled or testers are impatient             Console Write   b       -     spinIndex     amp  3

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This works if you want to make generating files look cool                    int num   1                  var spin   new ConsoleSpinner                    Console ForegroundColor   ConsoleColor Green                  Console Write                      while  true                                        spin Turn                        Console Write   r 0  Generating Files    num                       num                        And this is the method that i got from some answer below and modified it     public class ConsoleSpinner               int counter           public void Turn                         counter                switch  counter   4                                case 0  Console Write       counter   0  break                  case 1  Console Write        break                  case 2  Console Write         break                  case 3  Console Write          break                  case 4  Console Write   r    break                            Thread Sleep 100               Console SetCursorPosition 23  Console CursorTop

[c#] How can I update the current line in a C# Windows Console App?

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