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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?
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 < 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.
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).
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 < 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 < 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 < 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.
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<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.
\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.
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();
}
}
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 < 100; i++) {
System.Console.Write( "\rProcessing {0}%...", i );
System.Threading.Thread.Sleep( 1000 );
}
System.Console.WriteLine();
}
public void Update(string data)
{
Console.Write(string.Format("\r{0}", "".PadLeft(Console.CursorLeft, ' ')));
Console.Write(string.Format("\r{0}", data));
}
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.
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);
}
}
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++) & 3]);
}
}
}
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 < n; ++i)
Console.Write("\b \b");
}
public void SetBackSpace()
{
if (TotalLine == 0)
{
backspace(OneLineCharNum);
}
else
{
TotalLine--;
while (TotalLine >= 0)
{
backspace(OneLineCharNum);
TotalLine--;
if (TotalLine >= 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 > 0)
{
TotalLine++;
}
if (TotalLine == 0)
{
Console.Write("{0}", content);
return;
}
int i = 0;
while (i < TotalLine)
{
int cNum = i * OneLineCharNum;
if (i < 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");
}
}
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 > strTextToPrint.Length Then
Console.Write(Convert.ToChar(13) & strTextToPrint.PadRight(strTextToPrint.Length + (intLastLength - strTextToPrint.Length), Convert.ToChar(" ")))
Else
Console.Write(Convert.ToChar(13) & strTextToPrint)
End If
intLastLength = strTextToPrint.Length
End Sub
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 > 0; secondsRemaining --)
{
double minutesPrecise = secondsRemaining / 60;
double minutesRounded = Math.Round(minutesPrecise, 0);
int seconds = Convert.ToInt32((minutesRounded * 60) - secondsRemaining);
Console.Write($"\rProcess will resume in {minutesRounded}:{String.Format("{0:D2}", -seconds)} ");
Thread.Sleep(1000);
}
Console.WriteLine("");
Inspired by #E.Lahu Solution, implementation of a bar progress with percentage.
public class ConsoleSpinner
{
private int _counter;
public void Turn(Color color, int max, string prefix = "Completed", string symbol = "■",int position = 0)
{
Console.SetCursorPosition(0, position);
Console.Write($"{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 < max; i++)
{
spinner.Append(i < nmb ? symbol : ".");
}
spinner.Append("]");
return spinner.ToString();
}
}
public static void Main(string[] args)
{
var progressBar= new ConsoleSpinner();
for (int i = 0; i < 1000; i++)
{
progressBar.Turn(Color.Aqua,100);
Thread.Sleep(1000);
}
}
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.");
}
}
The SetCursorPosition method works in multi-threading scenario, where the other two methods don't
This question already has answers here:
Pass extra parameters to an event handler?
(10 answers)
Closed 3 years ago.
I for some reason am not able to call another method through the timer and use a variable "x" to input a value into that method using the timer
so if anyone could please show me how to properly get a input from the user into that ExecMain method it would be greatly appreciated :)
static void Main(string[] args)
{
// Timer.
var t = new Timer(TimerCallback, null, 0, 2000);
// Prevent the app from closing
Console.ReadLine();
}
private static void TimerCallback(Object o)
{
Console.Clear();
ExecMain(x); //This is where i want to to add a "int x = Convert.ToInt32(Console.ReadLine());"
} //So i basically want it to execute the "ExecMain" method every 2 seconds with the "x" input
static void ExecMain(int input)
{
int treeHeight = input, Space, sX;
Console.WriteLine("Tree:");
for (int i = 1; i <= treeHeight; i++) //Height loop
{
for (Space = 1; Space <= (treeHeight - i); Space++) //space loop
Console.Write(" ");
for (sX = 1; sX <= i; sX++) //left x loop with random ornaments
Console.Write(GetChar(GetRand()));
for (sX = (i - 1); sX >= 1; sX--) //right x loop with random ornaments
Console.Write(GetChar(GetRand()));
Console.WriteLine();
}
for (int k = 1; k <= (treeHeight - 2); k++)
{
Console.Write(" ");
}
Console.Write("| |");
Console.WriteLine();
Console.ReadLine();
}
One way of solving this is to make the value entered available globally. You then need to fix your sequence so that you read the value, write the tree for the first time, then kick off the timer:
private int _size;
static void Main(string[] args)
{
//Get the value from user first
_size = Convert.ToInt32(Console.Readline());
//Execute the first draw
ExecMain(_size);
// Start the timer
var t = new Timer(TimerCallback, null, 0, 2000);
// Prevent the app from closing
Console.ReadLine();
}
private static void TimerCallback(Object o)
{
Console.Clear();
ExecMain(_size); //This is where i want to to add a "int x = Convert.ToInt32(Console.ReadLine());"
}
I am not sure how the Console.Readline() to prevent closing and the Console.Clear() from the callback will interact though. It may not do what you think.
If you want to execute a method every 2 seconds and wait for user input you could just put it in a loop, which would eliminate the Timer object, that needs to be created:
using System.Threading
static void Main()
{
string input = Convert.ToInt32(Console.ReadLine());
while(true)
{
Console.Clear();
ExecMain(input);
Thread.Sleep(2000);
}
}
I'm new to programming and currently I'm trying to learn c#. Here is my question:
I have this following piece of code:
static void Main()
{
string loading = "LOADING...";
for (int i = 0; i < 5; i++)
{
foreach (var letter in loading)
{
Console.Write("{0}", letter);
Thread.Sleep(250);
}
Console.Clear();
Console.Write("\r");
}
for (int k = 0; k <= 100; k++)
{
Console.Write("\r{0}%", k);
Thread.Sleep(150);
}
}
I am trying to find a way to execute these two for loops simultaneously. I want to keep re-writing LOADING on the console and under it to print the percentage from 1 to 100. Right now the second for loop runs after the first quits. Is it possible to make them run at the same time? I have been trying to find an answer for a few hours now, but with no luck so far.
Thanks!
As krillgar noted you can use Tasks to run each loop independently. Something like this:
string loading = "LOADING...";
var loadingTask = Task.Run(() =>
{
for (int i = 0; i < 5; i++)
{
foreach (var letter in loading)
{
Console.Write("{0}", letter);
Thread.Sleep(250);
}
Console.Clear();
Console.Write("\r");
}
});
var pocTask = Task.Run(() =>
{
for (int k = 0; k <= 100; k++)
{
Console.Write("\r{0}%", k);
Thread.Sleep(150);
}
});
Task.WaitAll(loadingTask, pocTask);
Please note however it'll not work as you would expect( first line with LOADING... and second with percentage). That would require some synchronization of displayed messages between those loops and I think that's whole another story and not in the scope of the answer to your question.
There is more to this challenge than just running the code in two threads. When multiple threads are attempting to write to the console simultaneously, you are likely to end up with race conditions, where one thread starts writing in the middle of another thread's output.
To protect against this, you need to enforce critical sections, which are regions of your code where only one thread can execute at any time. These would generally consist of:
// Critical section
lock (syncLock)
{
Console.SetCursorPosition(x, y);
Console.Write(yourText);
}
Thread.Sleep(yourDelay);
Here is the full code:
// Dummy object to serve as mutual-exclusion lock when synchronizing threads.
private static readonly object syncLock = new object();
public static void Main(string[] args)
{
// Run two anonymous functions in parallel,
// then wait for both to complete.
Parallel.Invoke(
// Anonymous function for printing "LOADING..."
() =>
{
const string loading = "LOADING...";
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < loading.Length; j++)
{
// Critical section
lock (syncLock)
{
Console.SetCursorPosition(j, 0);
Console.Write("{0}", loading[j]);
}
Thread.Sleep(250);
}
// Critical section
lock (syncLock)
{
Console.SetCursorPosition(0, 0);
Console.Write("\r ");
}
Thread.Sleep(250);
}
},
// Anonymous function for printing "x%"
() =>
{
for (int k = 0; k <= 100; k++)
{
// Critical section
lock (syncLock)
{
Console.SetCursorPosition(0, 1);
Console.Write("\r{0}%", k);
}
Thread.Sleep(150);
}
});
}
}
I'm a beginner in C#. I'm developing a console game and I have a problem with Thread in C#.
My game will display a top bar where count down timer runs. I try with a thread, I use Console.Clear() to clear old number then replace by new number on one line (59,58,57...). My game display a message to user input user's data on center screen or anywhere,...etc. But, when I start the thread countdown, it clear console screen, also, it clear message that user can input user's data. Can you help me and explain how to start 2 threads, do more various tasks?
using System; using System.Threading;
namespace ConsoleApplication1 {
class Program {
static void Main(string[] args) {
Program m = new Program();
Thread pCountDown = new Thread(new ThreadStart(
m.DisplayCountDown
));
Thread pDisplayForm = new Thread(new ThreadStart(
m.DisplayForm
));
pCountDown.Start();
pDisplayForm.Start();
Console.ReadKey();
}
private void DisplayCountDown() {
for (int i = 60; i >= 0; --i) {
Console.Write("Time: {0}",i);
Thread.Sleep(1000);
Console.Clear();
}
}
private void DisplayForm() {
while (true) {
Console.Write("Enter your number: ");
int a = Int32.Parse(Console.ReadLine());
Console.WriteLine(a);
Console.ReadLine();
}
}
}
}
Error:
My error
I want like this:
Image (Sorry, i'm a new member): Like this
You don't need thread nor to clear the console. Simply use Console.SetCursorPosition() and Console.Write() as suggested here, so you can overwrite the number.
You do not need to clear the console. Console.Write() writes over the existing characters, so just change the cursor position with Console.SetCursorPosition(x,y);
For example:
string mystring = "put what you want to right here";
Console.SetCursorPosition(0,0); //the position starts at 0 just make a note of it
Conolse.Write(mystring);
//now when you are ready to clear the text and print something over it again
//just add this
//now first erase the previous text
for(int i = 0; i< mystring.Length; i++)
{
Console.SetCursorPosition(i,0);
Console.Write(' ');
}
//now write your new text
mystring = "something else";
Console.SetCursorPosition(0,0);
Console.Write("mystring");
Here's a sample DisplayCountDown which doesn't clear the whole screen every second:
private void DisplayCountDown()
{
for (int i = 20; i >= 0; --i)
{
int l = Console.CursorLeft;
int t = Console.CursorTop;
Console.CursorLeft = 0;
Console.CursorTop = 0;
Console.Write("Time: {0} ", i);
Console.CursorLeft = l;
Console.CursorTop = t;
Thread.Sleep(1000);
}
}
However, this still leaves some issues. In my case I saw "Enter your number" appearing on the top line and being overwritten, so had to add the line
if (Console.CursorTop == 0) Console.CursorTop = 1;
inside the while loop. Also, if the user enters enough numbers, the countdown scrolls out of view, and if you try to scroll up to look at it, setting the cursor position automatically scrolls back.
I also had intermittent issues with int.Parse throwing an exception, presumably caused by the countdown changing at some critical point of the user's input.
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?
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 < 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.
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).
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 < 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 < 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 < 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.
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<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.
\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.
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();
}
}
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 < 100; i++) {
System.Console.Write( "\rProcessing {0}%...", i );
System.Threading.Thread.Sleep( 1000 );
}
System.Console.WriteLine();
}
public void Update(string data)
{
Console.Write(string.Format("\r{0}", "".PadLeft(Console.CursorLeft, ' ')));
Console.Write(string.Format("\r{0}", data));
}
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.
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);
}
}
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++) & 3]);
}
}
}
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 < n; ++i)
Console.Write("\b \b");
}
public void SetBackSpace()
{
if (TotalLine == 0)
{
backspace(OneLineCharNum);
}
else
{
TotalLine--;
while (TotalLine >= 0)
{
backspace(OneLineCharNum);
TotalLine--;
if (TotalLine >= 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 > 0)
{
TotalLine++;
}
if (TotalLine == 0)
{
Console.Write("{0}", content);
return;
}
int i = 0;
while (i < TotalLine)
{
int cNum = i * OneLineCharNum;
if (i < 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");
}
}
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 > strTextToPrint.Length Then
Console.Write(Convert.ToChar(13) & strTextToPrint.PadRight(strTextToPrint.Length + (intLastLength - strTextToPrint.Length), Convert.ToChar(" ")))
Else
Console.Write(Convert.ToChar(13) & strTextToPrint)
End If
intLastLength = strTextToPrint.Length
End Sub
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 > 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("");
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 < max; i++)
{
spinner.Append(i < nmb ? symbol : ".");
}
spinner.Append("]");
return spinner.ToString();
}
}
public static void Main(string[] args)
{
var progressBar= new ConsoleSpinner();
for (int i = 0; i < 1000; i++)
{
progressBar.Turn(Color.Aqua,100);
Thread.Sleep(1000);
}
}
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.");
}
}
The SetCursorPosition method works in multi-threading scenario, where the other two methods don't