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Why is the console window closing immediately once displayed my output?
(15 answers)
Closed 7 years ago.
I'm learning to program in C# and I'm having problems with the console, when I run the code below the console show the output but immediately close the window and I can't see anything. I don't know what to do to keep the window open. Any suggestion? I'll be very grateful.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace testApp_1
{
class Program
{
static void Main(string[] args)
{
String word = "Hello world!";
Console.WriteLine(word);
}
}
}
This happens because when you reach the last line, you also reach the end of the program, thus it terminates. To keep the console window open, just add
Console.ReadKey() as the last line.
The execution continues after writing to the console and then the program exits. you need to do something to pause the execution, usually you would read something from the console:
Console.ReadKey();
to pause until the user presses a key
so your whole program might look like:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace testApp_1
{
class Program
{
static void Main(string[] args)
{
String word = "Hello world!";
Console.WriteLine(word);
//if you want the user to exit with any key press do this
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
//if you want the user to hit 'enter' to exit do this
Console.WriteLine("Press enter to exit.");
Console.ReadLine();
}
}
}
you can read about Console.ReadKey and Console.ReadLine on MSDN
Your code closes immediately, because it doesn't have anything else to do. What you'll want to do is to add this to the bottom of your code:
Console.Readline();
That will cause it to wait until you press Enter.
You can use following method to read some user input:
https://msdn.microsoft.com/de-de/library/system.console.readline%28v=vs.110%29.aspx
But you have to do some input.
You can also use logger frameworks: log4net:
http://logging.apache.org/log4net/
Console.ReadLine() is missing.
If you hit ctrl + F5 ( run without debugging) it will not close. But if you run with debugging, it will close after execution.
You can use Console.ReadLine(); in the end to wait for the user to hit return.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace testApp_1
{
class Program
{
static void Main(string[] args)
{
String word = "Hello world!";
Console.WriteLine(word);
Console.ReadLine();
}
}
}
Related
I'm making a c# console .net framework application to open the file Error.vbs, and I want to be able to choose the location of the started file's window on the desktop.
This is the code I have so far:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
namespace ErrorRunner
{
internal class Program
{
static void Main(string[] args)
{
Process ExternalProcess = new Process();
ExternalProcess.StartInfo.FileName = #"C:\Users\video\Downloads\Error.vbs";
while (true)
{
ExternalProcess.Start();
}
}
}
}
How would I choose the start location of error.vbs?
(And yes, I know it might be a bad idea to start a process indefinitely, but that's the whole purpose of this program.)
You can retrieve the external process window handle by using ExternalProcess.MainWindowHandle. Maybe you need to wait for process to start completely (see https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.process.mainwindowhandle?view=net-6.0#System_Diagnostics_Process_MainWindowHandle)
So you can use the handle with a P/Invoke to SetWindowPos (see https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setwindowpos)
I've been following along a book I've been studying as I'm rather new to C# and one of the projects is to create a date of birth calculator using the console template on VSC. Now i'm sure I've followed the tutorial correctly but for some reason my program close on the last line to present the entered information and outputs
exited with code 0 (0x0)
This is what I've got:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace HelloWorldAgain
{
class Program
{
static void Main(string[] args)
{
string userName = "";
int userAge = 0;
int currentYear = 0;
Console.Write("Please enter your name: ");
userName = Console.ReadLine();
Console.Write("Please enter your age: ");
userAge = Convert.ToInt32(Console.ReadLine());
Console.Write("Please enter current year: ");
currentYear = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Hello World! My name is {0} and I am {1} years old. I was born in {2}.", userName, userAge, currentYear - userAge);
}
}
}
Console applications are designed to run and exit. You should add something to prevent it from finishing before you want it to. The standard way to do this is to wait for input using:
Console.ReadLine();
Add the Readline() to the end of your code:
Console.WriteLine("Hello World! My name is {0} and I am {1} years old. I was born in {2}.", userName, userAge, currentYear - userAge);
Console.ReadLine()
The exit 0 code means that the program has been finished without errors. After the last line, there is nothing left to execute, which means the application have done their job. If you want to keep the application "executing", you may use the trick of Console.ReadLine() , which simply wait to read something.
Exiting with code 0 is perfectly normal and generally indicates your program ran successfully.
If you run a console program from visual studio with the debugger it will close the terminal window when your program completes. IF you run without the debugger it will generally keep the window open until you press a key.
If you want the terminal to stay open in the debugger then either add a breakpoint to the last line of your code or add an additional Console.Readline at the end of your program
So i was searching a way to set a hotkey to be able to exit a console application.
On my way i found this thread: Global hotkey in console application
which helped me a lot.
So basically i am setting a hotkey to exit my application. My code looks like this:
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Threading;
namespace ConsoleHotKey
{
class Program
{
static void Main(string[] args)
{
HotKeyManager.RegisterHotKey(Keys.A, KeyModifiers.Alt);
HotKeyManager.HotKeyPressed += new EventHandler<HotKeyEventArgs>(HotKeyManager_HotKeyPressed);
Console.ReadLine();
}
static void HotKeyManager_HotKeyPressed(object sender, HotKeyEventArgs e)
{
Environment.Exit(1);
}
}
}
and my question is: Is it a good way to exit a console application like this?
I found some poeple saying that it is not such a good way but i couldn't understand why.
Can someone give me some clarifications please?
I am trying to create a super basic consol application why does the consol display for less then half a second and then exit?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace MyHelloWorldApplication
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Test");
}
}
}
You are doing nothing after the Console.Writeline() method so the app will close.
Adding a Console.ReadKey() will stop the app from closing until you have pressed a key.
If you are using VisualStudio try CTRL + F5 or just F5 key. One of them will do the trick.
F5 - Will let you to run the application with debugging enabled.
CTRL + F5 - Will run application with out debugging.
Or Try:
Console.ReadLine();
At the end of Main method which will let program run until Enter key is pressed.
I presume you're debugging, in which case it disappears because execution of your program has finished.
Add a Console.ReadLine(); call to the end of your main method and it won't exit until you hit the return key.
it starts, runs, writes "Test" then closes.
add
Console.ReadLine();
after your WriteLine("Test") and it'll wait for you to press ENTER before closing.
using System.Threading;
Thread.Sleep(500);//500 msec.
In a C# .NET GUI Application. I also need the console in the background for some tasks. Basically, I'm using a Thrid Party library for some processing (takes lot of time) which writes its intermediate results to console. This processing is a computationally time taking task. So, I'm assigning this task to backgroundworker. I mean background worker calls these library functions. But problem is there is no way for me to show the user status of computation, because I don't have source of the library. I was hoping Console will be shown. But surprisingly Console.WriteLine doesn't seem to work. I mean, there isn't any console window shown. How come?
EDIT:
I tried setting application type = console. But there seems to be a problem. Only, main thread is able to access the console. Only Console.WriteLines executed by main (Application) thread are displayed on console. Console.WriteLines executed by other (BackgroundWorker)threads of the GUI, the output is not shown. I need console only for Background workers. I mean, When background worker starts, console starts & when it ends console will be off.
Create your own console window and use the Console.SetOut(myTextWriter); method to read anything written to the console.
Set your application type to "Console Application". Console applications can also create GUI windows with no problem, and write to the console at the same time.
If you don't have control of the main application, and you want to make sure that a console is shown, you can p/invoke AllocConsole (signature here).
This isn't the same as being a console application though, your application will always get a separate console window, which might be surprising to someone who launched it from a command prompt window. You can work around that with AttachConsole (signature and example here) but shell redirection of the output still won't work. That's why I suggest setting the application subsystem to console if you can.
Followed by #jgauffin, here is the implementation of Console.SetOut method.
Create a TextWriter inherited class.
using System;
using System.Text;
using System.IO;
using System.Windows.Forms;
namespace ConsoleRedirection
{
public class TextBoxStreamWriter : TextWriter
{
TextBox _output = null;
public TextBoxStreamWriter(TextBox output)
{
_output = output;
}
public override void Write(char value)
{
base.Write(value);
_output.AppendText(value.ToString()); // When character data is written, append it to the text box.
}
public override Encoding Encoding
{
get { return System.Text.Encoding.UTF8; }
}
}
}
And in the Form, code as below.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
namespace ConsoleRedirection
{
public partial class FormConsole : Form
{
// That's our custom TextWriter class
TextWriter _writer = null;
public FormConsole()
{
InitializeComponent();
}
private void FormConsole_Load(object sender, EventArgs e)
{
// Instantiate the writer
_writer = new TextBoxStreamWriter(txtConsole);
// Redirect the out Console stream
Console.SetOut(_writer);
Console.WriteLine("Now redirecting output to the text box");
}
// This is called when the "Say Hello" button is clicked
private void txtSayHello_Click(object sender, EventArgs e)
{
// Writing to the Console now causes the text to be displayed in the text box.
Console.WriteLine("Hello world");
}
}
}
Original code is from https://saezndaree.wordpress.com/2009/03/29/how-to-redirect-the-consoles-output-to-a-textbox-in-c/
You can check the link for cross-thread calls and advanced implementations at comments.