There is a problem in the code

[rezas1000]

Hello
The following code is correct:

#include <QtWidgets>
class DigitalClock : public QLCDNumber
{
    Q_OBJECT
 
public:
    DigitalClock(QWidget *parent = 0);
 
private slots:
    void showTime();
};

#include <QtWidgets>
class DigitalClock : public QLCDNumber
{
    Q_OBJECT

public:
    DigitalClock(QWidget *parent = 0);

private slots:
    void showTime();
};

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#include <QtWidgets>
#include "u.h"
DigitalClock::DigitalClock(QWidget *parent)
    : QLCDNumber(parent)
{
    setSegmentStyle(Filled);
 
    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));
    timer->start(1000);
 
    showTime();
 
    setWindowTitle(tr("Digital Clock"));
    resize(150, 60);
}
void DigitalClock::showTime()
{
      [COLOR="#FF0000"] QTime time = QTime:: currentTime(); [/COLOR]
    QString text = time.toString("hh:mm");
    if ((time.second() % 2) == 0)
        text[2] = ' ';
    display(text);
}

#include <QtWidgets>
#include "u.h"
DigitalClock::DigitalClock(QWidget *parent)
    : QLCDNumber(parent)
{
    setSegmentStyle(Filled);

    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));
    timer->start(1000);

    showTime();

    setWindowTitle(tr("Digital Clock"));
    resize(150, 60);
}
void DigitalClock::showTime()
{
      [COLOR="#FF0000"] QTime time = QTime:: currentTime(); [/COLOR]
    QString text = time.toString("hh:mm");
    if ((time.second() % 2) == 0)
        text[2] = ' ';
    display(text);
}

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#include <QApplication>
 
#include "u.h"
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    DigitalClock clock;
    clock.show();
    return app.exec();
}

#include <QApplication>

#include "u.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    DigitalClock clock;
    clock.show();
    return app.exec();
}

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and pro is;

QT += gui core widgets
SOURCES += \
main.cpp \
u.cpp

HEADERS += \
u.h

But when I change the colored part as follows:

Not run as before:

QTime time ; time. currentTime();

QTime time ; time. currentTime();

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thanks

[wysota]

The two following piece of code:

QTime time = QTime::currentTime();

QTime time = QTime::currentTime();

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is not equivalent to:

QTime time; time.currentTime();

QTime time; time.currentTime();

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The first one assigns the return value of QTime::currentTime() to the 'time' variable, the second one doesn't assign anything anywhere resulting in the 'time' variable containing its default (invalid time) value.

[rezas1000]

Hello
If the code is correct :

digitalClock::digitalClock(QWidget *parent)

: QLCDNumber(parent) {
....
....


The following code should be correct?!!!!!!!!

class a
{public:
a(int x):int(x){}
};

Please explain
thanks.

[anda_skoa]

No, why do you think it should be?

Cheers,
_

[rezas1000]

No, why do you think it should be?

Cheers,
_

Because int is a data type And QLCDNumber is data type.

for QLCDNumber,What happens in the following code?


digitalClock::digitalClock(QWidget *parent)

: QLCDNumber(parent) {
.....
.....

[anda_skoa]

But digitalClock is related to QLCDNumber, it is derived from it (a subclass of QLCFNumber).
The code is calling the base class constructor with an argument provided to the subclass constructor.

There is no such relation between "a" and "int".

Cheers,
_

[rezas1000]

The following code :

#include <QtWidgets>
#include "u.h"
DigitalClock::DigitalClock(QWidget *parent)
: QLCDNumber(parent)
{
setSegmentStyle(Filled);
 
QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));
timer->start(1000);
 
showTime();
 
setWindowTitle(tr("Digital Clock"));
resize(150, 60);
}
void DigitalClock::showTime()
{
[COLOR="#FF0000"] QTime time = QTime:: currentTime(); [/COLOR]
QString text = time.toString("hh:mm");
if ((time.second() % 2) == 0)

#include <QtWidgets>
#include "u.h"
DigitalClock::DigitalClock(QWidget *parent)
: QLCDNumber(parent)
{
setSegmentStyle(Filled);
 
QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));
timer->start(1000);
 
showTime();
 
setWindowTitle(tr("Digital Clock"));
resize(150, 60);
}
void DigitalClock::showTime()
{
[COLOR="#FF0000"] QTime time = QTime:: currentTime(); [/COLOR]
QString text = time.toString("hh:mm");
if ((time.second() % 2) == 0)

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"this",where to point?
thanks.

[Lesiok]

The following code :
"this",where to point?
thanks.

Where ever that is, shows himself - in this case, the object of the class DigitalClock.

[faldzip]

It seems that you do not have basic C++ knowledge, which is required to create a more complex application than "hello world".
My advice is to start from the beginning - get the C++ book and start with the HelloWorld and then slowly get through the classes and structs to inheritance and virtual functions. Then you'll be ready to develop your Qt application, as this is the knowledge you *must* have.
For example: You can't write the book in German language if you don't know this language, right? First you have to learn German and then start writing a book.