自定义信号使用

sig.h

#ifndef SIG_H
#define SIG_H

#include <QtGui/QDialog>
#include <QLabel>
#include <QPushButton>

class sig : public QDialog
{
	Q_OBJECT

public:
	sig(QWidget *parent = 0, Qt::WFlags flags = 0);
	~sig();
public slots:
	void showTimes(void);
public:signals:
	void mySig(QString str);
private:
	QLabel *showTime;
	QPushButton* getTimeBtn;
};

#endif // SIG_H

sig.cpp

#include <QTime>
#include "sig.h"

sig::sig(QWidget *parent, Qt::WFlags flags)
	: QDialog(parent, flags)
{
	this->resize(400, 500);
	showTime = new QLabel(this);
	getTimeBtn = new QPushButton(this);
	showTime->resize(200,50);
	showTime->move(150, 50);
	getTimeBtn->move(150,400);
	connect(getTimeBtn, SIGNAL(clicked()), this, SLOT(showTimes()));
	connect(this,SIGNAL(mySig(QString)), showTime, SLOT(setText(QString)));
}

sig::~sig()
{

}

void sig::showTimes(void)
{
	QString str = QTime::currentTime().toString("hh:mm:ss");
	emit mySig(str);
}    

main.cpp

#include "sig.h"
#include <QtGui/QApplication>

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	sig w;
	w.show();
	return a.exec();
}