一起看代码来玩玩QT之13 IO(one 基本)

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MyWidget.h

#ifndef MYWIDGET_H#define MYWIDGET_H#include <QWidget>class MyWidget : public QWidget{    Q_OBJECTpublic:    explicit MyWidget(QWidget *parent = 0);signals:public slots:};#endif // MYWIDGET_H

MyWidget.cpp

#include "MyWidget.h"#include <QFile>#include <QApplication>#include <QDebug>#include <QBuffer>#include <QLabel>#include <QTextStream>#include <QDataStream>/*    QFile    QBuffer // memory file    QTcpSocket    QUdpSocket    QDataStream  // io method    QTextStream*/MyWidget::MyWidget(QWidget *parent) :    QWidget(parent){#if 0    QFile file("../MyTest.txt");    file.open(QIODevice::ReadWrite);    file.write(QByteArray("abc"));    // file.seek   // file.write()    file.close();#endif#if 0    QBuffer buffer;    buffer.open(QIODevice::ReadWrite);    buffer.write("abc");    buffer.write("aabbcc");    buffer.close();    qDebug() << buffer.buffer();#endif#if 0    // send side    QBuffer buffer;    buffer.open(QIODevice::ReadWrite);    QPixmap pixmap("../aaa.png");    pixmap.save(&buffer, "PNG");    buffer.close();    qDebug() << buffer.buffer().size();    // recv side    QPixmap pixmap2;    pixmap2.loadFromData(buffer.buffer(), "PNG");    QLabel* label = new QLabel(this);    label->setPixmap(pixmap2);#endif#if 0    QByteArray ba("哈哈");    QString str("哈哈");    qDebug() << ba.size() << str.size();#endif#if 0    QFile file("../teststream.txt");    file.open(QIODevice::ReadWrite);    QTextStream textStream(&file);    textStream << 1 << "abc" << 1.2 << QString("abc");    file.close();#endif#if 0    QFile file("../datastream.txt");    file.open(QIODevice::ReadWrite);    QDataStream dataStream(&file);    dataStream << 1 << "abc" << 1.2 << QString("abc") << QPoint(1, 1);    file.close();#endif#if 0    QFile file("../datastream.txt");    file.open(QIODevice::ReadWrite);    QDataStream dataStream(&file);    int i;    char* buf;    double d;    QString str;    QPoint pt;    dataStream >> i >> buf >> d >> str >> pt;    delete[] buf;    qDebug() << i << buf << d << str << pt;    file.close();#endif#if 0    // virtual memory    QFile file("../map.txt");    file.open(QIODevice::ReadWrite);    file.seek(65535);    file.write("1");    file.close();    file.open(QIODevice::ReadWrite);    uchar* ptr = file.map(0, 64*1024);    // write file    *ptr = 'a';    ptr[1] = 'b';    // read file    uchar ch = *ptr;    file.unmap(ptr);    file.close();#endif}int main(int argc, char** argv){    QApplication app(argc, argv);    MyWidget w;    w.show();    return app.exec();}

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