Counter example for slot and signal is not working (symbol(s) not found for architecture x86_64)

[CroCo]

I'm trying to run the Counter example in this link http://doc.qt.io/qt-5/signalsandslots.html but I get linker error. This is I've done

project.pro
@QT += core
QT -= gui
CONFIG -= app_bundle
TEMPLATE = app
TARGET = test
SOURCES += main.cpp
@

main.cpp

@#include <QtCore>
#include <QVector>
#include <QObject>

class Counter : public QObject
{
Q_OBJECT

public:
Counter() { m_value = 0; }

int value() const { return m_value; }

public slots:
void setValue(int value);

signals:
void valueChanged(int newValue);

private:
int m_value;
};

void Counter::setValue(int value)
{
if (value != m_value) {
m_value = value;
emit valueChanged(value);
}
}

int main()
{
Counter a, b;
QObject::connect(&a, &Counter::valueChanged,
&b, &Counter::setValue);

a.setValue(12); // a.value() == 12, b.value() == 12
b.setValue(48); // a.value() == 12, b.value() == 48

return 0;
}
@

in the terminal

@> qmake -makefile project.pro

make @

I got this error

@/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -c -pipe -O2 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -Wall -W -fPIE -DQT_NO_DEBUG -DQT_CORE_LIB -I../../Qt5.2.1/5.2.1/clang_64/mkspecs/macx-clang -I. -I../../Qt5.2.1/5.2.1/clang_64/lib/QtCore.framework/Versions/5/Headers -I. -F/Users/bandarhd/Qt5.2.1/5.2.1/clang_64/lib -o main.o main.cpp
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -headerpad_max_install_names -Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -mmacosx-version-min=10.6 -o test main.o -F/Users/bandarhd/Qt5.2.1/5.2.1/clang_64/lib -framework QtCore
Undefined symbols for architecture x86_64:
"Counter::valueChanged(int)", referenced from:
Counter::setValue(int) in main.o
_main in main.o
"Counter::staticMetaObject", referenced from:
_main in main.o
"vtable for Counter", referenced from:
_main in main.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [test] Error 1
@

I'm using
@Mac OS X 10.9.4
QMake version 3.0
Using Qt version 5.2.1 in /Users/XXX/Qt5.2.1/5.2.1/clang_64/lib@

[SGaist]

Hi,

It's not a full featured example, these are code snippets to illustrate the theory of Signals and Slots.

You should rather take a look at the various full examples like the Calculator example which has code and explanation.

[Pradeep P N]

Hi,

This might help you and this is how you can use your signal to connect to your slot.

@QObject::connect(&a, SIGNAL(valueChanged(int)),&b,SLOT(setValue(int)));@

[edit: added missing coding tags @ SGaist]

[SGaist]

The example is showing the new notation.

However the code snippets don't constitute a full example.