#ifndef DIALOG_H
#define DIALOG_H
 
#include <QDialog>
#include <QLabel>
#include <QPushButton>
#include <QTimer>
#include <QStringList>
 
class Dialog : public QDialog
{
 Q_OBJECT
 
public:
 Dialog(QWidget *parent = 0);
 ~Dialog();
private slots:
 void on_clicked();
 void on_timer();
private:
 QLabel *label1;
 QPushButton *btn1;
 QTimer *tm;
 QStringList strlist;
};
 
 
#endif // DIALOG_H

#include "dialog.h"
#include <QVBoxLayout>
#include <QFont>
#include <QFile>
#include <QTextStream>
#include <QMessageBox>
 
Dialog::Dialog(QWidget *parent)
 : QDialog(parent)
{
 setWindowTitle(tr("幸運大抽獎"));//設置窗口標題
 label1 = new QLabel;
 label1->setText(tr("開始幸運大抽獎"));
 QFont font;
 font.setBold(true);//設置字體為粗體
 font.setPointSize(80);//設置字號
 label1->setFont(font);
 
 btn1 = new QPushButton;
 btn1->setText(tr("開始"));
 
 QVBoxLayout *layout1 = new QVBoxLayout(this);
 layout1->addWidget(label1, 0, Qt::AlignCenter);//加入label1標簽，并且居中顯示
 layout1->addWidget(btn1);
 // layout1->setSizeConstraint(QLayout::SetFixedSize);//設置layout大小和控件尺寸一致,使窗口不能更改大小
 
 QFile file("student.txt");
 if (file.open(QFile::ReadOnly))//以只讀的方式打開student.txt文件
 {
  QTextStream stream(&file);
  while(!stream.atEnd())
  {
   strlist.append(stream.readLine());//將文件內容放到strlist中
  }
  file.close();
 }else
 {
  //如果打開student.txt文件失敗,程序退出
  QMessageBox::critical(this, tr("錯誤"), file.errorString());
  exit(0);
 }
 tm = new QTimer(this);
 connect(tm, SIGNAL(timeout()), this, SLOT(on_timer()));
 connect(btn1, SIGNAL(clicked()), this, SLOT(on_clicked()));
}
 
Dialog::~Dialog()
{
 
}
 
void Dialog::on_clicked()
{
 static bool status = true;
 if (status)
 {
  btn1->setText("停止");//如果isok為true,設置按鈕標題為“停止”
  tm->start(50);//啟動計時器,沒0.05秒執(zhí)行一次on_timer函數(shù)
  status = false;
 }else
 {
  btn1->setText("開始");//如果isok為false,設置按鈕標題為“開始”
  tm->stop();//停止計時器
  status = true;
 }
}
 
void Dialog::on_timer()
{
 if (strlist.count() == 0)
 {
  return ;//如果strlist中沒有內容，函數(shù)返回
 }
 
 static int i = 0;
 label1->setText(strlist[i]);//從0到strlist.count(),循環(huán)顯示strlist中每一項的內容
 i++;
 if (i >= strlist.count())
 {
  i = 0;
 }
}