I have a C++ console application that prints some output constantly while it also accepts commands (using std::cin) from the user - output and input happen in separate threads.
If I write a text while some output appears the written text is mixed with application output. How can I prevent this behaviour?
To solve this problem, I need to display the program one line above the line where the text is typed. I'd inspire myself in Minecraft Bukkit server's solution - however I need the same for C++.
Assuming you want the output to appear while things are being typed, you'll need some screen control facilities to have the output go somewhere different than the input area. If I were tasked to implement something like this writing to a terminal I would refresh my ncurses experience. I realize you are on a Windows console and I have no idea if the Windows console is capable of the screen control needed to make it happen.
You can possibly tie custom stream buffers into std::cin and std::cout using the curses functionality under the hood but it may not be worth it. In any case, it isn't entirely trivial.
There's a windows port of ncurses called pdcurses. But if you are using visual studio there's a simple function provided called SetConsoleCursorPosition()
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I have an console application 'app.exe', which i want to invoke from a C++ program and then communicate with it as if it was a command line. Essentially I want to make a C++ wrapper around another console application so that I could pass input to it at will and receive output.
In pseudo-code something like:
std:string input("...some parameters..."), output;
Process app("app.exe");
app.InputOutput(input, output);
std::cout<<output;
This must have been answered already, but I seem to lack proper terminology to look it up.
In case it matters, I am running Eclipse CDT on Windows 10 with GCC 5.3.0
EDIT: I need to be able to repeatedly send some values to 'app.exe' and repeatedly receive response, rather than just invoke it with parameters. This is needed for a small personal project so I do not care about it being platform-specific.
I used this code as a starting point, in an MFC dialog, to display output from a called process. It was rather painless as this is well documented. He tells you why he is doing what. It should be suitable as you are working with the Windows platform. But as Alf points out, cross platform is something else.
You can use the system function to invoke a shell (command line) command.
That command can be to execute a program with the arguments you want.
system returns the process exit code, but for other results there is no direct support. One easy way to access the output, for a program that just does a job and ends, is to redirect the program's output to a file.
Otherwise you'll have to use communication mechanisms such as pipes or Windows mailslots, that are not supported by the C++ standard library, i.e. you're then into platform-specific code.
I am working on a windows sever program using c++, when the program started it stays for several days and output important logs to the default windows console.
now I want to add some control function to the console, like I cound enter something like query or stop, and the program ouput the variable number or stop accept requests. So there is the problem, I got two output stream(log and query response) and one input stream both mixed in one single console.
How do I seperate the three different stream in one single console? Maybe I cound write my own console to replace the default windows console?
I believe this is a very normal need and a lot of server application has implemented this but I could not find any source code...
I know I could use ncurses, but I think ncurses seems too low level for this. Any suggestion will be apprecitated.
As you can see in u413.com: Text comes on the screen, letter by letter, which looks kind of cool,
I want to do the same thing in Console
I got the source code of version 1.2; because I dont need all the complexity of version 2;
I just need a simple Command Prompt, with text that comes on to the screen letter by letter.
I dont need most of the builtin functions offered by Console, like Transparency, Taskbar Icon, etc.
The source code base is pretty small with only about 5 files.
The main class file seems to be Console.cpp;
Since console is like a GUI application, things dont get written to the STDOUT.
but heres what happens;
A Handle is called;
And that handle apparently writes to the console;
m_hStdOut = ::GetStdHandle(STD_OUTPUT_HANDLE);
Now what I want to be able to do; Is somehow read the handle; see what text it has; And throw in a loop with a ::Sleep(20) method in it; to make sure that text appears letter by letter.
#Alf P. Steinbach I wrote the psuedo code for making the sleep command(in java) I also made use of it in every other java program I wrote, but the disadvantage was that it will work only for my programs and not every program run in the command prompt, but what I dont know is code to make a console, a windows console subsystem program, I wish it was possible with java, so that I could use it on linux too, but now, let me ask you exactly what I had in mind...
A program which simply, took input from the screen, send it to cmd.exe for processing, and sent back the reply, and all I have to do is throw in a sleep command between every character...
All I need is help, in getting this done, I wish you could start me up with this, and possible provide links and refrences to get this done...
This Console.cpp seems like a console emulator, meaning it runs OTHER programs. You don't need the source code, you can run existing console applications.
STD_INPUT_HANDLE, STD_OUTPUT_HANDLE and STD_ERROR_HANDLE are the windows handles for STDIN, STDOUT and STDERR. They basicly does the same with only a few differences in how to use it.
If you want to integrate the console into your code, then you have to understand it, and find its own output function and call that. But it won't be any standard handle or things like that.
I'm trying to make a C++ console application using Xcode 4.1, but I can't find the command for cleaning the screen while the program is executing...
Any ideas? Thanks!
OSX doesn't have "consoles" the way Windows does. It has pseudoterminals, which act like an old-fashioned glass terminal to the program running "inside" them, and like a bidirectional pipe to the program that set them up. That outer program can do whatever it likes with the inner program's input and output. Notable examples of such programs are Terminal.app, which emulates the venerable VT-100, and ssh, which forwards the I/O over a secure channel to its own controlling terminal (which is probably itself a pseudoterminal). This is all by way of saying that there isn't a method that's guaranteed to work, because maybe the program on the outside of the pseudoterminal doesn't have a "screen" that you can meaningfully "clear." (Expect is a good example of a program like that.)
Having said that, though, if there is a screen, these days you can pretty much count on it to respect the VT-100 control codes. So this should do what you want:
std::cout << "\033[2J" << std::flush;
If you find that you need even one more control code, though, it's time to hook your program up to ncurses, which presents a nice friendly API to all the tricks that modern terminal windows are capable of, and will also have your back in the increasingly unlikely event that your program is attached to a terminal (or a program emulating a terminal) that is not a VT-100 nor one of its descendants.
I have a problem with my application win32 console.
The console is used to give commands to my application. However, at the same time it is used to output log messages which mostly comes from asynchronous threads. This becomes a problem when the user tries to write some input and simultaneously an async log message is printed, thus thrashing the display of the users input.
I would like to have some advice in regards to how to handle such a situtation?
Is it possible for example to dedicate the last line in the console to input, similarly to how it looks in the in-game consoles for some games?
You can use SetConsoleMode to disable input echo and line editing mode. You can then echo back input whenever your program is ready to do so. Note that this means you will need to implement things like backspace manually. And don't forget to reset the mode back when you're done with the console!
This is possible using the Console API, but it involves quite a bit of work and all the threads that use the console will have to cooperate by calling your output method rather than directly calling the Console API functions or the runtime library output functions.
The basic idea is to have your common output function write to the console screen buffer, and scroll the buffer in code rather than letting the text flow onto the last line and scroll automatically. As I recall, you'll have to parse the output for newlines and other control characters, and handle them correctly.
You might be able to get away with using "cooked" console input on the last line, although in doing so you risk problems if the user enters more text than will fit on a single line. Also, the user hitting Enter at the end of the line might cause it to scroll up. Probably best in this situation to use raw console input.
You'll want to become very familiar with Windows consoles.
Any time you have asyncronous threads trying to update the same device at once, you are going to have issues like this unless something synchronizes them.
If you have access to everyone's source code, the thing to do would probably be to create some kind of sync object that every task must use to access the console (semaphore, etc).