So I have been experimenting with the Gtkmm, as I want to migrate some of my code to C++ and I figured it would be easier.
I used to be able to use something that looks like so in C:
g_signal_connect(entry, "key-release-event", G_CALLBACK(receiveKeyPressed), NULL);
But it seems when I try to use the similar system in Gtkmm:
entry->signal_key_pressed().connect( sigc::ptr_fun(*receiveKeyPressed) );
It entirely misses all keyboard presses except for the shift keys and tab, etc.
Can anyone please explain why?
Connect your handler as first:
Flags: Run Last
#include <gtkmm.h>
#include <iostream>
int main()
{
auto app = Gtk::Application::create();
Gtk::Window window;
Gtk::Entry entry;
window.add(entry);
entry.signal_key_press_event().connect([&](GdkEventKey* event)->bool{
std::cout<<"pressed: "<<std::hex<<event->keyval<<" "<<std::hex<<event->state<<std::endl;
return false; //to propagate the event further
}, false); //run before other handlers (from entry)
window.show_all();
return app->run(window);
}
This is a fairly simple problem I can't get my head around. It was working before and suddenly now that I'm using std::cout, in the Visual Studio 2013 output window I do not see the output, but I see a bunch of background executions happening. I feel I have messed up something. This is App Game Kit project using C++.
Here's the simple code to output:
#include "template.h"
#include <iostream>
using namespace AGK;
app App;
void app::Begin(void)
{
agk::SetVirtualResolution (1024, 768);
agk::SetClearColor( 151,170,204 );
agk::SetSyncRate(60,0);
agk::SetScissor(0,0,0,0);
std::cout << "Hello"; // SIMPLE PRINT
}
void app::Loop (void)
{
agk::Print( agk::ScreenFPS() );
agk::Sync();
// std::cout << "Hello"; // TRIED HERE TOO (works like update() in Unity3D)
}
This is what my debug window is showing, instead of printing "Hello":
FYI, the program is working perfectly without any errors. Am I looking at the wrong window? where can find my output?
for logging, i write my entries to a file. here is the Contents of my log method in cpp:
void MyFileUtils::log(string msg)
{
ofstream log("logfile.txt", ios_base::app | ios_base::out);
log << msg << endl;
return;
}
i then just call this whenever i want to log something. i have it as a singleton. Then i just look in my media subfolder to see the contents of logfile.txt
Try using this before you return from the method:
log.flush();
log.close();
I just recently started playing around with SFML and I wrote this simple program.
I'm using visual studio 2010 btw.
The program compiles and runs fine when using the "start debugging" option.
but if I open the .exe file as if I was running a normal desktop application or something, it will crash on exit.
I've spent a while trying to figure it out but all I can say is that it's probably a heap corruption.
here's all the code:
#include <iostream>
#include <sstream>
#include <SFML/System.hpp>
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
void moveSquare();
void avgFPS();
class displayFPS : public sf::Thread{
public:
private:
virtual void Run();
};
int checkEvent(sf::RenderWindow &win){
sf::Event Event;
while(win.GetEvent(Event)){
// Window closed
if (Event.Type == sf::Event::Closed){
return 0;
}
// Escape key pressed
if ((Event.Type == sf::Event::KeyPressed) && (Event.Key.Code == sf::Key::Escape)){
return 0;
}
}
return -1;
}
sf::RenderWindow win(sf::VideoMode(800,600,32),"Mario Clone Test");
sf::Image img1(200,200,sf::Color(255,255,0));
sf::Sprite sprite1;
std::stringstream ss;
sf::String fps;
bool threadFPS;
int main(){
sprite1.SetImage(img1);
sprite1.SetCenter(-300,-300);
win.SetFramerateLimit(30);
moveSquare();
win.Close();
sf::Sleep(0.5);
return 0;
}
void moveSquare(){
displayFPS dispFPS;
threadFPS = true;
dispFPS.Launch();
fps.SetSize(20);
while(1){
if(!win.IsOpened() || checkEvent(win) == 0){
threadFPS = false;
dispFPS.Wait();
break;
}
win.Draw(sprite1);
win.Draw(fps);
win.Display();
win.Clear();
if(win.GetInput().IsKeyDown(sf::Key::Left)){
sprite1.Move(-100*win.GetFrameTime(),0);
}
if(win.GetInput().IsKeyDown(sf::Key::Right)){
sprite1.Move(100*win.GetFrameTime(),0);
}
if(win.GetInput().IsKeyDown(sf::Key::Up)){
sprite1.Move(0,-100*win.GetFrameTime());
}
if(win.GetInput().IsKeyDown(sf::Key::Down)){
sprite1.Move(0,100*win.GetFrameTime());
}
}
return;
}
void avgFPS(){
double frames=0.0,avg=0.0;
int j=0;
while(threadFPS){
if(win.GetFrameTime() != 0){
j++;
frames = frames+(1.0/win.GetFrameTime());
avg = frames/j;
}
ss << "avg FPS: " << avg << std::endl << "Arrow Keys to Move" << std::endl << "Press ESC to Exit";
fps.SetText(ss.str());
ss.str("");
}
return;
}
void displayFPS::Run(){
avgFPS();
}
I've had the same issue.
You need to recompile SFML when using VS2010.
Few things for you to try:
If you are suspecting heap corruption, run gflags (found in Debugging Tools for Windows) and enable page heap. Some instructions on how it works can be found here. Basically when page heap is enabled, your app will crash at the point of the memory error, not sometime later.
You said you get a crash on exit. When that happens, I'm assuming windows throws up a crash dialog box. Open one of those links that say something like "see what information is being uploaded". Somewhere among those files will be a minidump of your process. You can load that up in visual studio (open file and hit F5). Sometimes visual studio is glitchy, so another, more reliable but more difficult but more difficult to use alternative is WinDbg, also part of Debugging Tools for Windows.
SFML has multiple versions of their .lib's for release and debug.
Examples:
sfml-audio.lib
sfml-audio-d.lib
sfml-audio-s.lib
sfml-audio-s-d.lib
Make sure you are using the lib without the -d in it.
Also, when you put the .dll's with your exe (assuming you are using the dynamic libraries) make sure to use the normal versions not the debug (-d) versions.
Finally, when you are building the project make sure you build for release and not debug.
I have a Qt GUI application running on Windows that allows command-line options to be passed and under some circumstances I want to output a message to the console and then quit, for example:
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
if (someCommandLineParam)
{
std::cout << "Hello, world!";
return 0;
}
MainWindow w;
w.show();
return a.exec();
}
However, the console messages do not appear when I run the app from a command-prompt. Does anyone know how I can get this to work?
Windows does not really support dual mode applications.
To see console output you need to create a console application
CONFIG += console
However, if you double click on the program to start the GUI mode version then you will get a console window appearing, which is probably not what you want. To prevent the console window appearing you have to create a GUI mode application in which case you get no output in the console.
One idea may be to create a second small application which is a console application and provides the output. This can call the second one to do the work.
Or you could put all the functionality in a DLL then create two versions of the .exe file which have very simple main functions which call into the DLL. One is for the GUI and one is for the console.
Add:
#ifdef _WIN32
if (AttachConsole(ATTACH_PARENT_PROCESS)) {
freopen("CONOUT$", "w", stdout);
freopen("CONOUT$", "w", stderr);
}
#endif
at the top of main(). This will enable output to the console only if the program is started in a console, and won't pop up a console window in other situations. If you want to create a console window to display messages when you run the app outside a console you can change the condition to:
if (AttachConsole(ATTACH_PARENT_PROCESS) || AllocConsole())
void Console()
{
AllocConsole();
FILE *pFileCon = NULL;
pFileCon = freopen("CONOUT$", "w", stdout);
COORD coordInfo;
coordInfo.X = 130;
coordInfo.Y = 9000;
SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), coordInfo);
SetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE),ENABLE_QUICK_EDIT_MODE| ENABLE_EXTENDED_FLAGS);
}
int main(int argc, char *argv[])
{
Console();
std::cout<<"start##";
qDebug()<<"start!";
You can't use std::cout as others have said,my way is perfect even for some code can't include "qdebug" !
So many answers to this topic. 0.0
So I tried it with Qt5.x from Win7 to Win10. It took me some hours to have a good working solution which doesn't produce any problems somewhere in the chain:
#include "mainwindow.h"
#include <QApplication>
#include <windows.h>
#include <stdio.h>
#include <iostream>
//
// Add to project file:
// CONFIG += console
//
int main( int argc, char *argv[] )
{
if( argc < 2 )
{
#if defined( Q_OS_WIN )
::ShowWindow( ::GetConsoleWindow(), SW_HIDE ); //hide console window
#endif
QApplication a( argc, argv );
MainWindow *w = new MainWindow;
w->show();
int e = a.exec();
delete w; //needed to execute deconstructor
exit( e ); //needed to exit the hidden console
return e;
}
else
{
QCoreApplication a( argc, argv );
std::string g;
std::cout << "Enter name: ";
std::cin >> g;
std::cout << "Name is: " << g << std::endl;
exit( 0 );
return a.exec();
}
}
I tried it also without the "CONFIG += console", but then you need to redirect the streams and create the console on your own:
#ifdef _WIN32
if (AttachConsole(ATTACH_PARENT_PROCESS) || AllocConsole()){
freopen("CONOUT$", "w", stdout);
freopen("CONOUT$", "w", stderr);
freopen("CONIN$", "r", stdin);
}
#endif
BUT this only works if you start it through a debugger, otherwise all inputs are directed towards the system too. Means, if you type a name via std::cin the system tries to execute the name as a command. (very strange)
Two other warnings to this attempt would be, that you can't use ::FreeConsole() it won't close it and if you start it through a console the app won't close.
Last there is a Qt help section in QApplication to this topic. I tried the example there with an application and it doesn't work for the GUI, it stucked somewhere in an endless loop and the GUI won't be rendered or it simply crashes:
QCoreApplication* createApplication(int &argc, char *argv[])
{
for (int i = 1; i < argc; ++i)
if (!qstrcmp(argv[i], "-no-gui"))
return new QCoreApplication(argc, argv);
return new QApplication(argc, argv);
}
int main(int argc, char* argv[])
{
QScopedPointer<QCoreApplication> app(createApplication(argc, argv));
if (qobject_cast<QApplication *>(app.data())) {
// start GUI version...
} else {
// start non-GUI version...
}
return app->exec();
}
So if you are using Windows and Qt simply use the console option, hide the console if you need the GUI and close it via exit.
No way to output a message to console when using QT += gui.
fprintf(stderr, ...) also can't print output.
Use QMessageBox instead to show the message.
Oh you can Output a message when using QT += gui and CONFIG += console.
You need printf("foo bar") but cout << "foo bar" doesn't works
Something you may want to investigate, at least for windows, is the AllocConsole() function in the windows api. It calls GetStdHandle a few times to redirect stdout, stderr, etc. (A quick test shows this doesn't entirely do what we want it to do. You do get a console window opened alongside your other Qt stuff, but you can't output to it. Presumably, because the console window is open, there is some way to access it, get a handle to it, or access and manipulate it somehow. Here's the MSDN documentation for those interested in figuring this out:
AllocConsole():
http://msdn.microsoft.com/en-us/library/windows/desktop/ms681944%28v=vs.85%29.aspx
GetStdHandle(...):
http://msdn.microsoft.com/en-us/library/windows/desktop/ms683231%28v=vs.85%29.aspx
(I'd add this as a comment, but the rules prevent me from doing so...)
I used this header below for my projects. Hope it helps.
#ifndef __DEBUG__H
#define __DEBUG__H
#include <QtGui>
static void myMessageOutput(bool debug, QtMsgType type, const QString & msg) {
if (!debug) return;
QDateTime dateTime = QDateTime::currentDateTime();
QString dateString = dateTime.toString("yyyy.MM.dd hh:mm:ss:zzz");
switch (type) {
case QtDebugMsg:
fprintf(stderr, "Debug: %s\n", msg.toAscii().data());
break;
case QtWarningMsg:
fprintf(stderr, "Warning: %s\n", msg.toAscii().data());
break;
case QtCriticalMsg:
fprintf(stderr, "Critical: %s\n", msg.toAscii().data());
break;
case QtFatalMsg:
fprintf(stderr, "Fatal: %s\n", msg.toAscii().data());
abort();
}
}
#endif
PS: you could add dateString to output if you want in future.
First of all, why would you need to output to console in a release mode build? Nobody will think to look there when there's a gui...
Second, qDebug is fancy :)
Third, you can try adding console to your .pro's CONFIG, it might work.
In your .pro add
CONFIG += console
It may have been an oversight of other answers, or perhaps it is a requirement of the user to indeed need console output, but the obvious answer to me is to create a secondary window that can be shown or hidden (with a checkbox or button) that shows all messages by appending lines of text to a text box widget and use that as a console?
The benefits of such a solution are:
A simple solution (providing all it displays is a simple log).
The ability to dock the 'console' widget onto the main application window. (In Qt, anyhow).
The ability to create many consoles (if more than 1 thread, etc).
A pretty easy change from local console output to sending log over network to a client.
Hope this gives you food for thought, although I am not in any way yet qualified to postulate on how you should do this, I can imagine it is something very achievable by any one of us with a little searching / reading!
Make sure Qt5Core.dll is in the same directory with your application executable.
I had a similar issue in Qt5 with a console application:
if I start the application from Qt Creator, the output text is visible,
if I open cmd.exe and start the same application there, no output is visible.
Very strange!
I solved it by copying Qt5Core.dll to the directory with the application executable.
Here is my tiny console application:
#include <QCoreApplication>
#include <QDebug>
int main(int argc, char *argv[])
{
int x=343;
QString str("Hello World");
qDebug()<< str << x<<"lalalaa";
QTextStream out(stdout);
out << "aldfjals alsdfajs...";
}
I also played with this, discovering that redirecting output worked, but I never saw output to the console window, which is present for every windows application. This is my solution so far, until I find a Qt replacement for ShowWindow and GetConsoleWindow.
Run this from a command prompt without parameters - get the window. Run from command prompt with parameters (eg. cmd aaa bbb ccc) - you get the text output on the command prompt window - just as you would expect for any Windows console app.
Please excuse the lame example - it represents about 30 minutes of tinkering.
#include "mainwindow.h"
#include <QTextStream>
#include <QCoreApplication>
#include <QApplication>
#include <QWidget>
#include <windows.h>
QT_USE_NAMESPACE
int main(int argc, char *argv[])
{
if (argc > 1) {
// User has specified command-line arguments
QCoreApplication a(argc, argv);
QTextStream out(stdout);
int i;
ShowWindow (GetConsoleWindow(),SW_NORMAL);
for (i=1; i<argc; i++)
out << i << ':' << argv [i] << endl;
out << endl << "Hello, World" << endl;
out << "Application Directory Path:" << a.applicationDirPath() << endl;
out << "Application File Path:" << a.applicationFilePath() << endl;
MessageBox (0,(LPCWSTR)"Continue?",(LPCWSTR)"Silly Question",MB_YESNO);
return 0;
} else {
QApplication a(argc, argv);
MainWindow w;
w.setWindowTitle("Simple example");
w.show();
return a.exec();
}
}
After a rather long struggle with exactly the same problem I found that simply
CONFIG += console
really does the trick. It won't work until you explicitly tell QtCreator to execute qmake on the project (right click on project) AND change something inside the source file, then rebuild. Otherwise compilation is skipped and you still won't see the output on the command line.
Now my program works in both GUI and cmd line mode.
One solution is to run powershell and redirect the output to whatever stream you want.
Below is an example of running powershell from cmd.exe and redirecting my_exec.exe output to both the console and an output.txt file:
powershell ".\my_exec.exe | tee output.txt"
An example (from cmd.exe) which holds open stdout/stderr and doesn't require tee or a temporary file:
my_exec.exe > NUL 2>&1
Easy
Step1: Create new project. Go File->New File or Project --> Other Project -->Empty Project
Step2: Use the below code.
In .pro file
QT +=widgets
CONFIG += console
TARGET = minimal
SOURCES += \ main.cpp
Step3: Create main.cpp and copy the below code.
#include <QApplication>
#include <QtCore>
using namespace std;
QTextStream in(stdin);
QTextStream out(stdout);
int main(int argc, char *argv[]){
QApplication app(argc,argv);
qDebug() << "Please enter some text over here: " << endl;
out.flush();
QString input;
input = in.readLine();
out << "The input is " << input << endl;
return app.exec();
}
I created necessary objects in the code for your understanding.
Just Run It
If you want your program to get multiple inputs with some conditions. Then past the below code in Main.cpp
#include <QApplication>
#include <QtCore>
using namespace std;
QTextStream in(stdin);
QTextStream out(stdout);
int main(int argc, char *argv[]){
QApplication app(argc,argv);
qDebug() << "Please enter some text over here: " << endl;
out.flush();
QString input;
do{
input = in.readLine();
if(input.size()==6){
out << "The input is " << input << endl;
}
else
{
qDebug("Not the exact input man");
}
}while(!input.size()==0);
qDebug(" WE ARE AT THE END");
// endif
return app.exec();
} // end main
Hope it educates you.
Good day,
First of all you can try flushing the buffer
std::cout << "Hello, world!"<<std::endl;
For more Qt based logging you can try using qDebug.