输入与输出 课本12 读取和写入二进制数据 一

工程代码：  1.rar  

c++ gui qt4 编程 page224

豆子：http://devbean.blog.51cto.com/448512/293892

#include <QApplication>
#include <QImage>
#include <QMap>
#include <QFile>
#include <QDataStream>
#include <QtGui>
#include <iostream>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
   // QCoreApplication app(argc,argv);

    QImage image("philip.png");
    QFile file("facts.dat");
    if(!file.open(QIODevice::WriteOnly))
    {
        std::cerr << "cann't open file for writing:";
        return 1;
    }

    QDataStream out(&file);
    out.setVersion(QDataStream::Qt_4_7);

    out<<quint32(0x12345678)<<image;//<<map;
    file.close();
/*****************存储结束*******************/

    quint32 n;
    QImage image1;
    QFile file1("facts.dat");
    if(!file1.open(QIODevice::ReadOnly))
    {
        std::cerr << "cannt't open file1 or reading";
        return 1;
    }

    QDataStream in(&file1);
    in.setVersion(QDataStream::Qt_4_7); //保证版本号一致
    in >> n >> image1;
    file1.close();
    if(n == 0x12345678) //测试读到的是否为原先的值
        std::cout << "n is ok\n";

    return 0;
}

QDataStream 的 QByteArray 格式

#include <QtCore/QCoreApplication>
#include <QByteArray>
#include <QDataStream>
#include <QDebug>

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);
  QByteArray data;
  QDataStream stream(&data,QIODevice::ReadWrite);
  QString str="elephant logon";
  QString strout;
  data.resize(100);
  stream<<str;
  stream.device()->seek(0);  //设置 流 到开始位置
  stream>>strout;
  qDebug()<<strout;
  return 0;
}