It just came to attention that every time we run the c# console application, at the end it shows text stating "Press any key to continue... ".
And the moment you hit any key, it terminates the console/program.
In actual program there is no mentioning about such text printing on standard output console, then from where and why it comes out on screen?
Can someone explain the logic behind?
Code:
static void Main(string[] args)
{
Console.WriteLine("Test Application");
}
Output:
Test Application
Press any key to continue . . .
It has nothing to do with your application itself. When you double-click on the output EXE file you'll not see it. It is only when we run the app from within Visual Studio without the debugger attached when this behavior is seen.
When you press Ctrl+F5, Visual Studio is running your app in a way that causes the console window to remain open.
I think it comes from cmd parameters that are used. Something like :
%COMSPEC% /k "C:\VS\MyApplication.exe"
Do you use CodeBlocks ?
If yes, it is a Feature of CodeBlocks. That you can read the Output without to write something like getChar() at the end that the console stay open. Otherwise it would close instantly and you can't read the output.
In normal application the console will close when done and that is the expected behaviour. This prompt simply helps you to check the results of your code when you are writing your application and you do not have to put (and remember about later removal) of the:
Console.ReadLine();
in your application just to test it and see what the output is.
Related
I'm learning how to make console apps in C# and when I tried using the exe in debug and release it opens then closes in like 0.1 millisecond anything I need to do to run the the exe
Use Console.ReadLine();
Reads the next line of characters from the standard input stream.
One of the most common uses of the ReadLine method is to pause the program
execution before clearing the console and displaying new information to
it, or to prompt the user to press the Enter key before terminating the
application.
Console.ReadLine();
This question already has answers here:
Why is the console window closing immediately once displayed my output?
(15 answers)
Closed 5 years ago.
My console applications on Visual Studio are closing automatically once the program finishes the execution. I'd like to "pause" the applications at the end of their execution so that I can easily check the output. How can I achieve that?
Update:
As of Visual Studio 2017, there's a built-in option in the IDE at:
Tools > Options > Debugging > Automatically close the console when debugging stops
Unchecking it will automatically pause the application at the end of the execution, allowing you the easily check its output without having to add extra code to your application.
There are two ways;
Console.ReadLine();
ReadLine() waits for ↩
or
Console.ReadKey();
ReadKey() waits for any key (except for modifier keys).
You can just compile (start debugging) your work with Ctrl+F5.
Try it. I always do it and the console shows me my results open on it. No additional code is needed.
Try Ctrl + F5 in Visual Studio to run your program, this will add a pause with "Press any key to continue..." automatically without any Console.Readline() or ReadKey() functions.
Console.ReadLine() to wait for the user to Enter or Console.ReadKey to wait for any key.
Use:
Console.ReadKey();
For it to close when someone presses any key, or:
Console.ReadLine();
For when the user types something and presses enter.
Alternatively, you can delay the closing using the following code:
System.Threading.Thread.Sleep(1000);
Note the Sleep is using milliseconds.
Ctrl + F5 is better, because you don't need additional lines.
And you can, in the end, hit enter and exit running mode.
But, when you start a program with F5 and put a break-point, you can debug your application and that gives you other advantages.
Those solutions mentioned change how your program work.
You can off course put #if DEBUG and #endif around the Console calls, but if you really want to prevent the window from closing only on your dev machine under Visual Studio or if VS isn't running only if you explicitly configure it, and you don't want the annoying 'Press any key to exit...' when running from the command line, the way to go is to use the System.Diagnostics.Debugger API's.
If you only want that to work in DEBUG, simply wrap this code in a [Conditional("DEBUG")] void BreakConditional() method.
// Test some configuration option or another
bool launch;
var env = Environment.GetEnvironmentVariable("LAUNCH_DEBUGGER_IF_NOT_ATTACHED");
if (!bool.TryParse(env, out launch))
launch = false;
// Break either if a debugger is already attached, or if configured to launch
if (launch || Debugger.IsAttached) {
if (Debugger.IsAttached || Debugger.Launch())
Debugger.Break();
}
This also works to debug programs that need elevated privileges, or that need to be able to elevate themselves.
If you do not want the program to close even if a user presses anykey;
while (true) {
System.Console.ReadKey();
};//This wont stop app
I created a blank C# console application in Visual Studio as shown below:
using System;
namespace ConsoleApplication1
{
class Solution
{
static void Main(string[] args)
{
Console.ReadLine();
}
}
}
When I use the default Start Debugging option by pressing F5 then the program runs normally as expected. I press Enter and program ends.
But when I use Start Without Debugging option by pressing Ctrl+F5 it shows me an extra message on console after I press Enter:
Press any key to continue...
Then I've to press an additional key on the keyboard to terminate the program. From where is this magical message coming and why it is shown only in Start Without Debugging option?
Note:Post-build event command line of the project is completely empty.
That is simply how visual studio runs console programs not in debug mode. As far as I am aware it can not be controlled. Since it shows that it is actually a cmd.exe instance and not just a console window I assume VS uses the /K flag on the command line (I had thought it used a batch file but now see there is no need for that).
It is done for the typical case where a console program runs and simply exits, without that message such a program would not give any chance to see the output.
I was able to validate the information shared by #SoronelHaetir in his answer. I'm detailing out the same here with the help of some screenshots which will complement the information in his post and help you understand the same better:
When I run the application using the default Start Debugging option by pressing F5, we can see the executable of the application getting launched in task manager:
When I right click on the task and choose Go To Process option from context menu, I'm taken to a process on the process tab having image name ConsoleApp1.exe *32 as shown below. This makes perfect sense.
Now when I run the application using Start Without Debugging option by pressing Ctrl + F5, we do not see the executable of the application getting launched in task manager. In fact we see cmd.exe being launched as shown below:
Now, when I right click on the cmd.exe task and choose Go To Process option from context menu, I'm taken to a process on the process tab having an image name cmd.exe *32 as shown below. But there is more to it. You also see ConsoleApp1.exe *32 running in the process tab which was not visible in Applications tab.
So this is how all the dots get connected that in Start Without Debugging mode Visual Studio in fact launches a cmd.exe instance which in turn launches our application ConsoleApp1.exe.
The moment I press enter, ConsoleApp1.exe process gets terminated but cmd.exe process continue to live on until I press another key as shown below:
This question already has answers here:
Why is the console window closing immediately once displayed my output?
(15 answers)
Closed 5 years ago.
My console applications on Visual Studio are closing automatically once the program finishes the execution. I'd like to "pause" the applications at the end of their execution so that I can easily check the output. How can I achieve that?
Update:
As of Visual Studio 2017, there's a built-in option in the IDE at:
Tools > Options > Debugging > Automatically close the console when debugging stops
Unchecking it will automatically pause the application at the end of the execution, allowing you the easily check its output without having to add extra code to your application.
There are two ways;
Console.ReadLine();
ReadLine() waits for ↩
or
Console.ReadKey();
ReadKey() waits for any key (except for modifier keys).
You can just compile (start debugging) your work with Ctrl+F5.
Try it. I always do it and the console shows me my results open on it. No additional code is needed.
Try Ctrl + F5 in Visual Studio to run your program, this will add a pause with "Press any key to continue..." automatically without any Console.Readline() or ReadKey() functions.
Console.ReadLine() to wait for the user to Enter or Console.ReadKey to wait for any key.
Use:
Console.ReadKey();
For it to close when someone presses any key, or:
Console.ReadLine();
For when the user types something and presses enter.
Alternatively, you can delay the closing using the following code:
System.Threading.Thread.Sleep(1000);
Note the Sleep is using milliseconds.
Ctrl + F5 is better, because you don't need additional lines.
And you can, in the end, hit enter and exit running mode.
But, when you start a program with F5 and put a break-point, you can debug your application and that gives you other advantages.
Those solutions mentioned change how your program work.
You can off course put #if DEBUG and #endif around the Console calls, but if you really want to prevent the window from closing only on your dev machine under Visual Studio or if VS isn't running only if you explicitly configure it, and you don't want the annoying 'Press any key to exit...' when running from the command line, the way to go is to use the System.Diagnostics.Debugger API's.
If you only want that to work in DEBUG, simply wrap this code in a [Conditional("DEBUG")] void BreakConditional() method.
// Test some configuration option or another
bool launch;
var env = Environment.GetEnvironmentVariable("LAUNCH_DEBUGGER_IF_NOT_ATTACHED");
if (!bool.TryParse(env, out launch))
launch = false;
// Break either if a debugger is already attached, or if configured to launch
if (launch || Debugger.IsAttached) {
if (Debugger.IsAttached || Debugger.Launch())
Debugger.Break();
}
This also works to debug programs that need elevated privileges, or that need to be able to elevate themselves.
If you do not want the program to close even if a user presses anykey;
while (true) {
System.Console.ReadKey();
};//This wont stop app
I just open a console application and I type
Console.WriteLine("Test");
But the output window doesn't show this. I go to the output window with Ctrl + W, O.
But nothing shows up when I run my program. Am I nuts or is this not supported in Visual Studio 2010 Express?
Console.WriteLine writes your output to the console window opened by your application (think black window with white text that appears when you open the Command Prompt.) Try System.Diagnostics.Debug.WriteLine instead.
No satisfactory answers were provided.
System.Diagnostics.Debug.WriteLine() will write messages to the Output:debug window, but so much crap is constantly dumped into that window by every process under the sun, it is like finding a needle in a haystack to find your messages.
Console.WriteLine() does not write to any window in Visual Studio. I guess it will only write to the application console if your application creates a console in the first place, i.e. if it is a console application.
Go to properties in you own project in the Solution Explorer window and choose application type and look for Output Type.
Change its value to Console Application.
This will make console screen besides your form. If you close the console screen, your form will be closed too.
Perhaps the console is clearing. Try:
Console.WriteLine("Test");
Console.ReadLine();
And it will hopefully stay there until you press enter.
Or you can debug by CTRL+F5 this will open ConsoleWindow waits after last line executed untill you press key.
It's more than likely because you've used Console in the namespace. For example like this:
namespace XYZApplication.Console
{
class Program
{
static void Main(string[] args)
{
//Some code;
}
}
}
Try removing it from the namespace or use the full namespace instead i.e.
System.Console.Writeline("abc");
The reason is a problem this is an issue is because you might have another clashing namespace. Example:
using System;
using AnotherNamespaceThatContainsAConsoleClass;
The output window isn't the console. Try the methods in System.Diagnostics.Debug
In a Windows Forms application, both methods,
System.Diagnostics.Debug.WriteLine("my string")
and
System.Console.WriteLine("my string")
write to the output window.
In an ASP.NET Core application, only System.Diagnostics.Debug.WriteLine("my string") writes to the output window.
Try Ctrl + F5. It will hold your screen until you press any key.
I run into a similar problem while running a unit test. Console.WriteLine() did not write anything into the Visual Studio Output Window.
Using System.Diagnostics.Debug.WriteLine() solved the problem.
None of the answers here worked for me!! Most of these people here are stuck in Windows Desktop Application Consoleland. If you are a web developer using ASP.NET in Visual Studio and do not see any console or debug text, here is how to fix that:
Paste the following two tests into your code so it runs both lines. These are tests for the output window:
System.Console.WriteLine($"hello console!");
System.Diagnostics.Debug.WriteLine($"hello debugger!");
In Visual Studio choose VIEW > OUTPUT. You will see the results above in this output window after changing two settings below.
When NOT DEBUGGING, in the OUTPUT window at the top under "Show Output From" choose: "YourProjectName - ASP.NET CORE Web Server". Run your code. You should see the "Console" text above.
When DEBUGGING, in the OUTPUT window at the top under "Show Output From" choose: "Debugger". Run your code in debug mode. You should see the "Debug" text above.
Right click on the project in Solution Explorer and click "Clean".
Now run - press F5.
Make sure the code is as below:
Console.WriteLine("TEST");
Console.ReadLine();
If you use Ctrl-F5 (start without debugging) it will leave the console window open with a message "Press any key to continue". That's the easiest way to keep the console window from closing so you can see the console output.
Go to the Debug menu and select Options and uncheck "Redirect all Output Window text to Immediate Window"
Console.Writeline() shows up in the debug output (Debug => Windows => Output).
If you are developing a command line application, you can also use Console.ReadLine() at the end of your code to wait for the 'Enter' keypress before closing the console window so that you can read your output.
using System.Diagnostics;
Trace.WriteLine("This line will show on Output window");
Trace.Flush();
This works on Microsoft Team Explorer for Visual Studio 2013
Refer to microsoft.com
The Output window of Visual Studio 2017 have a menu called Show output from, in my case ASP.NET Core Web Server was the option to select in order to see the printed out, I came across this issue since I had it set to Build so I wasn't seeing the printed out lines at runtime.
There are 2 possible problems are:
Firstly, you have not used the using System which should be before writing code that uses "System class", as Console.WriteLine()
Secondly, you have not coded what happens after the Console displays "Test"
The possible solution will be:
using System;
namespace Test
{
public static Main()
{
//Print to the console
Console.WriteLine("Test");
//Allow user to read output
Console.ReadKey();
}
}
It is also strategic to code Console.Write("Press any key to exit..."); on the line that precedes the Console.ReadKey(); to make the user aware that the program is ending, he/she must press any key to exit.
Change the execution mode to "Self Hosted". In this case, the execution console will appear and all the messages will be displayed.
A workaround I found:
Press Ctrl + Alt + I or navigate to the Debug tab → Windows → Immediate.
In your code write:
Trace.WriteLine("This is one of the workarounds");