When I run my program, the console window seems to run and close. How to keep it open so I can see the results?
class Program
{
public class StringAddString
{
public virtual void AddString()
{
var strings2 = new string[] { "1", "2", "3", "4", "5","6", "7", "8", "9"};
Console.WriteLine(strings2);
Console.ReadLine();
}
}
static void Main(string[] args)
{
StringAddString s = new StringAddString();
}
}
Put a Console.Read() as the last line in your program. That will prevent it from closing until you press a key
static void Main(string[] args)
{
StringAddString s = new StringAddString();
Console.Read();
}
If you want to keep it open when you are debugging, but still let it close normally when not debugging, you can do something like this:
if (System.Diagnostics.Debugger.IsAttached) Console.ReadLine();
Like other answers have stated, the call to Console.ReadLine() will keep the window open until enter is pressed, but Console.ReadLine() will only be called if the debugger is attached.
There are two ways I know of
1) Console.ReadLine() at the end of the program. Disadvantage, you have to change your code and have to remember to take it out
2) Run outside of the debugger CONTROL-F5 this opens a console window outside of visual studio and that window won't close when finished. Advantage, you don't have to change your code. Disadvantage, if there is an exception, it won't drop into the debugger (however when you do get exceptions, you can simply just rerun it in the debugger)
Console.ReadKey(true);
This command is a bit nicer than readline which passes only when you hit enter, and the true parameter also hides the ugly flashing cursor while reading the result :) then any keystroke terminates
You forgot calling your method:
static void Main(string[] args)
{
StringAddString s = new StringAddString();
s.AddString();
}
it should stop your console, but the result might not be what you expected, you should change your code a little bit:
Console.WriteLine(string.Join(",", strings2));
You can handle this without requiring a user input.
Step 1. Create a ManualRestEvent at the start of Main thread
ManualResetEvent manualResetEvent = new ManualResetEvent(false);
Step 2 . Wait ManualResetEvent
manualResetEvent.WaitOne();
Step 3.To Stop
manualResetEvent.Set();
Write Console.ReadKey(); in the last line of main() method. This line prevents finishing the console. I hope it would help you.
If your using Visual Studio just run the application with Crtl + F5 instead of F5. This will leave the console open when it's finished executing.
Use Console.Readline() at the end .Your code will not close until you close it manually.Since Readline waits for input that needs to be entered for your code hence your console will be open until you type some input.
For visual c# console Application use:
Console.ReadLine();
Console.Read();
Console.ReadKey(true);
for visual c++ win32 console application use:
system("pause");
press ctrl+f5 to run the application.
Make sure to useConsole.ReadLine();
to keep the preceeding Console.WriteLine(""); message from closing.
Console.Read()
-> Console stays open until you press a button on your keyboard
To be able to give it input without it closing as well you could enclose the code in a while loop
while (true)
{
<INSERT CODE HERE>
}
It will continue to halt at Console.ReadLine();, then do another loop when you input something.
If you're using Visual Studio, then the IDE has an option to keep the window open under
Tools > Options > Debugging >
Automatically close the console when debugging stops
Unlike CTRL + F5, this allows you to use breakpoints while debugging.
Related
I'm studying C# by following the guides in MSDN.
Now, I just tried the Example 1 (here is the link to MSDN), and I've encountered an issue: why is the console window closing immediately once displayed my output?
using System;
public class Hello1
{
public static int Main()
{
Console.WriteLine("Hello, World!");
return 0;
}
}
the issue here is that their Hello World Program is showing up then it would immediately close.
why is that?
Because it's finished. When console applications have completed executing and return from their main method, the associated console window automatically closes. This is expected behavior.
If you want to keep it open for debugging purposes, you'll need to instruct the computer to wait for a key press before ending the app and closing the window.
The Console.ReadLine method is one way of doing that. Adding this line to the end of your code (just before the return statement) will cause the application to wait for you to press a key before exiting.
Alternatively, you could start the application without the debugger attached by pressing Ctrl+F5 from within the Visual Studio environment, but this has the obvious disadvantage of preventing you from using the debugging features, which you probably want at your disposal when writing an application.
The best compromise is probably to call the Console.ReadLine method only when debugging the application by wrapping it in a preprocessor directive. Something like:
#if DEBUG
Console.WriteLine("Press enter to close...");
Console.ReadLine();
#endif
You might also want the window to stay open if an uncaught exception was thrown. To do that you can put the Console.ReadLine(); in a finally block:
#if DEBUG
try
{
//...
}
finally
{
Console.WriteLine("Press enter to close...");
Console.ReadLine();
}
#endif
Instead of using
Console.Readline()
Console.Read()
Console.ReadKey()
you can run your program using Ctrl+F5 (if you are in Visual Studio). Then Visual Studio will keep the console window open, until you press a key.
Note: You cannot debug your code in this approach.
I assume the reason you don't want it to close in Debug mode, is because you want to look at the values of variables etc. So it's probably best to just insert a break-point on the closing "}" of the main function.
If you don't need to debug, then Ctrl-F5 is the best option.
This behaves the same for CtrlF5 or F5.
Place immediately before end of Main method.
using System.Diagnostics;
private static void Main(string[] args) {
DoWork();
if (Debugger.IsAttached) {
Console.WriteLine("Press any key to continue . . .");
Console.ReadKey();
}
}
In Visual Studio 2019 for .NET Core projects the console doesn't close automatically by default. You can configure the behaviour through menu Tools → Options → Debugging → General → Automatically close the console when debugging stops. If you get your console window automatically closing, check if the mentioned setting is not set.
The same applies to the .NET Framework new style console projects:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net472</TargetFramework>
</PropertyGroup>
</Project>
The old style .NET Framework project still unconditionally close the console at the end (as of Visual Studio 16.0.1).
Reference: .NET Core tooling update for Visual Studio 2019 Preview 2
If you want to keep your application opened, you have to do something in order to keep its process alive. The below example is the simplest one, to be put at the end of your program:
while (true) ;
However, it'll cause the CPU to overload, as it's therefore forced to iterate infinitely.
At this point, you can opt to use System.Windows.Forms.Application class (but it requires you to add System.Windows.Forms reference):
Application.Run();
This doesn't leak CPU and works successfully.
In order to avoid to add System.Windows.Forms reference, you can use a simple trick, the so-called spin waiting, importing System.Threading:
SpinWait.SpinUntil(() => false);
This also works perfectly, and it basically consists of a while loop with a negated condition that is returned by the above lambda method. Why isn't this overloading CPU? You can look at the source code here; anyway, it basically waits some CPU cycle before iterating over.
You can also create a message looper, which peeks the pending messages from the system and processes each of them before passing to the next iteration, as follows:
[DebuggerHidden, DebuggerStepperBoundary, DebuggerNonUserCode, DllImport("user32.dll", EntryPoint = "PeekMessage")]
public static extern int PeekMessage(out NativeMessage lpMsg, IntPtr hWnd, int wMsgFilterMin, int wMsgFilterMax, int wRemoveMsg);
[DebuggerHidden, DebuggerStepperBoundary, DebuggerNonUserCode, DllImport("user32.dll", EntryPoint = "GetMessage")]
public static extern int GetMessage(out NativeMessage lpMsg, IntPtr hWnd, int wMsgFilterMin, int wMsgFilterMax);
[DebuggerHidden, DebuggerStepperBoundary, DebuggerNonUserCode, DllImport("user32.dll", EntryPoint = "TranslateMessage")]
public static extern int TranslateMessage(ref NativeMessage lpMsg);
[DebuggerHidden, DebuggerStepperBoundary, DebuggerNonUserCode, DllImport("user32.dll", EntryPoint = "DispatchMessage")]
public static extern int DispatchMessage(ref NativeMessage lpMsg);
[DebuggerHidden, DebuggerStepperBoundary, DebuggerNonUserCode]
public static bool ProcessMessageOnce()
{
NativeMessage message = new NativeMessage();
if (!IsMessagePending(out message))
return true;
if (GetMessage(out message, IntPtr.Zero, 0, 0) == -1)
return true;
Message frameworkMessage = new Message()
{
HWnd = message.handle,
LParam = message.lParam,
WParam = message.wParam,
Msg = (int)message.msg
};
if (Application.FilterMessage(ref frameworkMessage))
return true;
TranslateMessage(ref message);
DispatchMessage(ref message);
return false;
}
Then, you can loop safely by doing something like this:
while (true)
ProcessMessageOnce();
The program immediately closes because there's nothing stopping it from closing. Insert a breakpoint at return 0; or add Console.Read(); before return 0; to prevent the program from closing.
Alternatively, you can delay the closing using the following code:
System.Threading.Thread.Sleep(1000);
Note the Sleep is using milliseconds.
Another way is to use Debugger.Break() before returning from Main method
The code is finished, to continue you need to add this:
Console.ReadLine();
or
Console.Read();
Use Console.Read(); to prevent the program from closing, but make sure you add the Console.Read(); code before return statement, or else it will be a unreachable code .
Console.Read();
return 0;
check this Console.Read
Add The Read method to show the output.
Console.WriteLine("Hello, World!");
Console.Read();
return 0;
Here is a way to do it without involving Console:
var endlessTask = new TaskCompletionSource<bool>().Task;
endlessTask.Wait();
Tools -> Options -> Debugging -> General -> Automatically close the console (5th last option)
Check the box and close.
This applied to all projects.
The program is closing as soon as its execution is complete.
In this case when you return 0;. This is expected functionality.
If you want to see the output then either run it in a terminal manually or set a wait at the end of the program so that it will stay open for a few seconds (using the threading library).
I'm trying to run a simple Hello World code in VSC 1.13.1.
using System;
public class Hello1
{
public static void Main()
{
Console.WriteLine("Hello, World!");
}
}
It successfully completes execution but doesnt produce any output ie - Hello, World!
Any help please!
Using Code Runner.
Add Console.ReadKey() , so the output will be there until the key is pressed
public static void Main()
{
Console.WriteLine("Hello, World!");
Console.ReadKey();
}
There currently seems to be a problem with VSCode (or the C# extension). Other StackOverflow answers show that this didn't work a few years ago, then it started working, and now (2018) it doesn't work once again.
I'm having the same problem. The workaround I found is this: If I run my code in the debugger (Debug > Start Debugging), it shows the output. But if I just run it normally, it doesn't. That's the only workaround I've found or read about that works for me.
Another option is to start the project with ctrl + F5 instead of just F5, it will keep the terminal open until you press a key as well
How to keep the console window open in Visual C++?
It have come to my attention that Using Code Runner, at this time, indeed produces some inconsistent behavior for JS as well.
However, on a first look you have not installed the proper supporting addons (which may be the cause for your particular problem):
Code Runner requires : "To run C# script, you need to install scriptcs"
Which is said to use Chocolatey - package manager for Windows.
For the moment, disabling the extension, restarting VSCode and then enabling it - fixed the current common problem for JS (not always producing an output). Which may be preceding with C#, as well.
NB! Make sure you save your files manually before you run them using Code Run
I will test this today and add the results.
Test Results: After installing scriptcs and Chocolatey your HelloWorld.cs file can run, BUT will not produce result.The reason: the code is treated as a script. Meaning that there is nothing invoking the Main() method. Meaning, you have to do it. Example:
using System;
public class Hello
{
public static void Main()
{
var message = "hiiii inside => Works" ;
Console.WriteLine(message);
HW();
}
public static void HW(){
Console.WriteLine("Hello, World!");
// the ReadLine will not work because it is only one way solution : ouptut only
// var a = Console.ReadLine();
// Console.WriteLine("key pressed: " + a + "Doesn't work");
}
}
Hello.Main();
//can be used like this as well
var message= "Hey helloooo outside WORKS";
Console.WriteLine(message);
Use Ctrl+Alt+N to start and Ctrl+Alt+M to stop(if hung). And it will hung, if you use Console.ReadLine(); - check(uncomment) the example code in the HW() method.
P.S. Namespaces can't be used in scripts - will be the error message you get, if you try to use them with Code Runner
Well, Code Runner is a tool to run C# script. It will treat the main method as a normal method and will not call it.
You should just write the Main method:
System.Console.WriteLine("hello, world");
or
static class Test
{
public static void Main()
{
System.Console.WriteLine("hello, world");
}
}
Test.Main();
I'm trying to run a program like a for loop. But when it starts debugging the console window disappears immediately. How do I stop this. I need something like press any key to continue.
Have a statement like
Console.Read()
That way, the console will remain until you press a key.
For more information, read here.
Write Console.ReadLine() or Console.Read() or Console.ReadKey() at the end of your program.
It will make your screen wait for your key press in order to exit.
I just found out that pressing the Ctrl + F5 key makes the console stay.
You didn't mention any example code. This is my example code. Program waits for pressing a key
class Program
{
static void Main(string[] args)
{
for (int i = 0; i < 3; i++)
{
Console.WriteLine(i);
}
Console.ReadKey();
}
}
I want to exit the console window as soon as my files are written in folder at back end, but no matter whatever I try,
Environment.exit(0);
Environment.exit(1);
Environment.exit(-1);
Also since I am executing from the Main method, I am returning the value, but still my console window doesn't go off even after files are written to the destination folder.
Below is my code,
static void Main(string[] args)
{
string execute = "";
execute = data_info_pooling(args[0], args[1], args[2]);
Environment.Exit(0);
}
Also I tried for using Application.exit();, but I am not able to get Application in drop-down box. I have explored almost all the possible helping links from Stack Overflow and searched for any help, but I have no idea where I am going wrong.
I am trying to run this console application by opening the command prompt and then executing the command as below
cd "Project Path\Debug"
"Project.exe" "First Parameter" " Second Parameter" "Third Parameter"`,
After files are written in the destination folder, the console window waits and after pressing Enter it just gives the path again to execute, but I want the window to exit as soon as the task of writing files is completed.
Second version of the code
I have deleted the for loop which is not necessary. Actually, I was wrong in application of my logic and apologize for my mistake. Some of the below comments helped me to realize my mistake. It's finally
Environment.exit();
Which works. Also I would like to give a try to another answer of forming batch.
Environment.Exit and Application.Exit
Environment.Exit(0) is cleaner.
You can also change the return value from void to int. Then you can simply return a ExitCode.
public static int Main(string[] args)
{
string execute = "";
for (int i = 0; i < args.Length; i++)
{
string argument = args[i];
execute = data_info_pooling(args[0], args[1], args[2]);
}
return -1
}
As soon as your console application ends, the command window, created for it (assuming you run it from Windows Explorer) will be closed automatically.
If, however, you open a command window first, to specify parameters when running the EXE file, then Explorer will not close it (obviously).
One possible solution is to wrap the session into a batch file. Create project.bat with the following content:
Project.exe "First Parameter" " Second Parameter" "Third Parameter"
; some other jobs
Running that batch file (from Windows Explorer directly) will pass parameters to your application and the command window will be closed upon the end.
It may be what you want.
Isn't there a better looking statement (or way) to keep the console from disappearing than the hackish Console.ReadLine() call. Something that's more expressive of the purpose of, more orthogonal to, keeping the Console visible ?
If you are still developing application you can run via Ctrl + F5 (Without debugging)
otherwise you can use Console.ReadKey() (same but there is no more option)
You can do:
Console.ReadKey();
Console.ReadLine() is not really hackish, your pausing the screen to wait for input. The input can either be a single key, or a string.
Update
One nice thing about the ReadKey() method is that it "waits, that is, blocks on the thread issuing the ReadKey method, until a character or function key is pressed." MSDN
This is different than ReadLine which takes in a string. Arguably, cleaner.
It depends on the context. If you're talking about running a command line, debugging through your code, and then being able to view the results on the console you have two options:
If you run with the debugger attached (f5), you must use Console.ReadLine
If you run without the debugger attached (ctrl + f5), it will stay open ... but then you obviously can't debug through.
I'm not sure why that's the default behavior, but there it is :-)
I usually use one of these:
Console.ReadKey(true); //You might want to put this in an infinite loop
new AutoResetEvent(false).WaitOne();
In VS You can also run (Ctrl + F5) the program (in distinction to running in debug) and it will add a system pause after it finishes executing.
I'd say that WaitOne, and just running (& not debugging) the program are your non-hackish options.
If you do want to debug, perhaps set a breakpoint at the last }.
Depends on what I am doing. If I am doing multi-threaded work and want my Console application to remain alive until all other work is done, I usually do something like this. (Similar to MasterMastic)
using System;
using System.Threading;
namespace Test_Console
{
class Program
{
static EventWaitHandle EWHandle;
static void Main(string[] args)
{
EWHandle = new EventWaitHandle(false, EventResetMode.AutoReset);
Thread WorkThread = new Thread(new ThreadStart(DoStuff));
EWHandle.WaitOne();
}
static void DoStuff()
{
Console.WriteLine("Do what you want here");
EWHandle.Set();
}
}
}
Of course, there's always just using the regular breakpoints and the other debugging tools if that's what you're going for.