Unable to create qwtPlot object

[jtso8]

I am currently trying to create a scatter plot but, I'm unsure of what the problem is. I found this code online and I was using it as a starting point but, I can't get the program to build. This is the code that I am using.

#include <cmath>
#include <QApplication>
#include <qwt-qt4/qwt_plot.h>
 
int main(int argc, char **argv)
{
  QApplication a(argc, argv);
 
  QwtPlot plot;
  plot.setGeometry(0,0,640,400);
  plot.setAxisScale(QwtPlot::xBottom, 0.0,2.0 * M_PI);
  plot.setAxisScale(QwtPlot::yLeft,-1.0,1.0);
 
  QwtPlotCurve sine("Sine");
  std::vector<double> xs;
  std::vector<double> ys;
  for (double x = 0; x < 2.0 * M_PI; x+=(M_PI / 10.0))
  {
    xs.push_back(x);
    ys.push_back(std::sin(x));
  }
  sine.setData(&xs[0],&ys[0],xs.size());
  sine.attach(&plot);
 
  plot.showFullScreen();
  return a.exec();
}

#include <cmath>
#include <QApplication>
#include <qwt-qt4/qwt_plot.h>

int main(int argc, char **argv)
{
  QApplication a(argc, argv);

  QwtPlot plot;
  plot.setGeometry(0,0,640,400);
  plot.setAxisScale(QwtPlot::xBottom, 0.0,2.0 * M_PI);
  plot.setAxisScale(QwtPlot::yLeft,-1.0,1.0);

  QwtPlotCurve sine("Sine");
  std::vector<double> xs;
  std::vector<double> ys;
  for (double x = 0; x < 2.0 * M_PI; x+=(M_PI / 10.0))
  {
    xs.push_back(x);
    ys.push_back(std::sin(x));
  }
  sine.setData(&xs[0],&ys[0],xs.size());
  sine.attach(&plot);
  
  plot.showFullScreen();
  return a.exec();
}

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The errors that I get don't really tell me anything. The errors tells me the file path of these things and says undefined reference to:
QwtPlot::QwtPlot(QWidget*)
QwtPlot::setAxisScale(...)
QwtPlot::setAxisScale(...)
QwtPlot::~QwtPlot()
QwtPlot::~QwtPlot()

just to name a few. Does anyone know a possible solution to this problem.

[Spitfire]

Link against Qwt...

QT += qwt
if you've used make install when compiling qwt or
LIBS += -L/path_to_qwt/lib -lqwt
if you haven't.

[jtso8]

I'm not sure what that means. I am running Ubuntu on my computer and i think i installed qwt when i used the code on their homepage to download the files. I can type #include <> and it will show qwt_qt4. I don't know if that helps any.

[Uwe]

I can type #include <> and it will show qwt_qt4. I don't know if that helps any.

What version of Qwt is it and - if it is a Qwt 6 - does the Ubuntu Package install the qwt.prf file ?

Uwe

[jtso8]

To install qwt I went to the homepage and used this:
svn co https://qwt.svn.sourceforge.net/svnr...anches/qwt-6.0
To install qwt and I'm unsure Id qwt.prf was installed as well but I will look for that later tonight. I know a file was created by qwt in my home directory.

[Uwe]

So you have built and compiled your own version of Qwt - not using the Ubuntu package.

Then there is not much more to say, than what is written in the INSTALL file of the Qwt tarball. Follow those advices step by step and ask if you have problems with one of them. This is much better than unspecific problem reports.

Uwe

[jtso8]

I did find a problem after i ran qmake everything was fine but while running make i got this error:

compiling qwt_plot.cpp
qwt_plot.cpp:10:22: fatal error: qwt_plot.h: No such file or directory
compilation terminated.
make[1]: *** [obj/qwt_plot.o] Error 1
make[1]: Leaving directory `/home/jeff/Downloads/qwt-6.0.1/src'
make: *** [sub-src-make_default-ordered] Error 2

I tried it again and got this error:


jeff@jeff-laptop:~/Downloads/qwt-6.0.1$ qmake
jeff@jeff-laptop:~/Downloads/qwt-6.0.1$ make
cd src/ && make -f Makefile
make[1]: Entering directory `/home/jeff/.local/share/Trash/files/qwt-6.0.1/src'
compiling qwt_plot.cpp
qwt_plot.cpp:10:22: fatal error: qwt_plot.h: No such file or directory
compilation terminated.
make[1]: *** [obj/qwt_plot.o] Error 1
make[1]: Leaving directory `/home/jeff/.local/share/Trash/files/qwt-6.0.1/src'
make: *** [sub-src-make_default-ordered] Error 2

[Uwe]

qwt_plot.h should be in the same directory as qwt_plot.cpp itself. If it is not there do a "svn update" to get a complete download.

When the compiler error remains edit qwtbuild.pri and disable the line "CONFIG += silent". Then check the include path, that it is passed to the compiler.

Uwe