Full error message


/MyFolder/main.o:: In function 'main':
/MyFolder/main.cpp:8: error: undefined reference to 'QwtPlot::QwtPlot(QWidget*)'
:: error: collect2: ld returned 1 exit status

Cause

Operating system: Ubuntu 10.04 LTS Lucid Lynx

IDE: Qt Creator 2.0.0

Project type: Console Application

Compiler: G++ 4.4.1

Libraries used:

Qt: version 4.7.0 (32 bit)

Qt project file


#-------------------------------------------------

#

# Project created by QtCreator 2010-07-21T19:21:43

#

#-------------------------------------------------

QT       += core gui

TARGET = CppQwtExample1

TEMPLATE = app

SOURCES += main.cpp

LIBS += -L/usr/local/lib -lqwt

Source code


#include <QApplication>



#include <qwt-qt4/qwt_plot.h>



int main(int argc, char **argv)

{

  QApplication a(argc, argv);

  QwtPlot plot;

  plot.show();

  return a.exec();

}

Solution

Do not link to qwt, but to qwt-qt. You will also need to link to QtSvg (otherwise the Undefined reference to 'QGraphicsItemPrivate::height() const' link error occurs).

Change the Qt Creator project file to the following:


#-------------------------------------------------
#
# Project created by QtCreator 2010-07-21T19:21:43
#
#-------------------------------------------------
QT       += core gui
TARGET = CppQwtExample1
TEMPLATE = app
SOURCES += main.cpp
LIBS += -L/usr/local/lib -lqwt-qt4
LIBS += -L/usr/local/lib -lQtSvg

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(C++) Undefined reference to 'QwtPlot::QwtPlot(QWidget*)'

Full error message

Cause

Qt project file

Source code

Solution