Qt 多种方式读写二进制文件

将文本数据写入二进制文件，然后从二进制文件中读出，还原为文本数据

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDataStream>

int main(int argc, char *argv[])  7 {  8  QApplication a(argc, argv);  9 
    //写二进制文件
    QFile file("F:/1.txt"); 12     if(!file.open(QIODevice::WriteOnly)) 13  { 14         qDebug() << "Can't open file for writing"; 15         return 0; 16  } 17     QDataStream out(&file); 18     out.setVersion(QDataStream::Qt_5_7); 19     out << int(12) << QByteArray("123"); 20  file.close(); 21 
    //读二进制文件
    if (!file.open(QIODevice::ReadOnly)) 24  { 25         qDebug() << "Cannot open file for reading: "; 26         return 0; 27  } 28     QDataStream in(&file); 29     in.setVersion(QDataStream::Qt_5_7); 30     int n; 31  QByteArray s; 32     in >> n >> s; 33  file.close(); 34     qDebug() << n << s; 35 
    return a.exec(); 37 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>

class T  7 {  8 public:  9     int a; 10     double b; 11  QString c; 12 
    T(int a1, double b1, QString c1); 14 
    friend QDataStream& operator<<(QDataStream &out, const T &t); 16     friend QDataStream& operator>>(QDataStream &in, T &t); 17 }; 18 
T::T(int a1, double b1, QString c1) 20 { 21     a = a1; 22     b = b1; 23     c = c1; 24 } 25 
QDataStream& operator <<(QDataStream &out, const T &t) 27 { 28     out << t.a << t.b << t.c; 29     return out; 30 } 31 
QDataStream& operator >>(QDataStream &in, T &t) 33 { 34     int a; 35     double b; 36  QString c; 37     in >> a >> b >> c; 38     t.a = a; 39     t.b = b; 40     t.c = c; 41     return in; 42 } 43 
int main(int argc, char *argv[]) 45 { 46  QApplication a(argc, argv); 47 
    //写二进制文件
    T t(1, 2, "3"); 50     QFile writeFile("1.dat"); 51  writeFile.open(QIODevice::WriteOnly); 52     QDataStream out(&writeFile); 53     out << t; 54  writeFile.close(); 55 
    //读二进制文件
    QFile readFile("1.dat"); 58  readFile.open(QIODevice::ReadOnly); 59     QDataStream in(&readFile); 60     in >> t; 61  readFile.close(); 62     qDebug() << t.a << t.b << t.c; 63 
    return 0; 65     return a.exec(); 66 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>

class T  7 {  8 public:  9     int a; 10     double b; 11  QString c; 12 
    T(int a1, double b1, QString c1); 14 }; 15 
T::T(int a1, double b1, QString c1) 17 { 18     a = a1; 19     b = b1; 20     c = c1; 21 } 22 

int main(int argc, char *argv[]) 25 { 26  QApplication a(argc, argv); 27 
    //写文件
    T t(1, 2, "34"); 30     QFile writeFile("1.dat"); 31  writeFile.open(QIODevice::WriteOnly); 32     QDataStream out(&writeFile); 33     out.writeRawData((char *)&t, sizeof(t)); 34  writeFile.close(); 35 
    //读文件
    QFile readFile("1.dat"); 38  readFile.open(QIODevice::ReadOnly); 39     QDataStream in(&readFile); 40     in.readRawData((char *)&t, sizeof(t)); 41  readFile.close(); 42     qDebug() << t.a << t.b << t.c; 43 
    return 0; 45     return a.exec(); 46 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>

int main(int argc, char *argv[])  7 {  8  QApplication a(argc, argv);  9 
    //写文件
    int aa = 1; 12     char b = 'c'; 13     double c = 2; 14     QFile writeFile("1.dat"); 15  writeFile.open(QIODevice::WriteOnly); 16     QDataStream out(&writeFile); 17     out.writeRawData((char *)&aa, sizeof(int)); 18     out.writeRawData((char *)&b, sizeof(char)); 19     out.writeRawData((char *)&c, sizeof(double)); 20  writeFile.close(); 21 
    //读文件
    QFile readFile("1.dat"); 24  readFile.open(QIODevice::ReadOnly); 25     QDataStream in(&readFile); 26     in.readRawData((char *)&aa, sizeof(int)); 27     in.readRawData((char *)&b, sizeof(char)); 28     in.readRawData((char *)&c, sizeof(double)); 29  readFile.close(); 30     qDebug() << aa << b << c; 31 
    return 0; 33     return a.exec(); 34 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>
int main(int argc, char *argv[])  6 {  7  QApplication a(argc, argv);  8 
    //写文件
    int aa = 1; 11     char b = 'c'; 12     double c = 2; 13     QFile writeFile("1.dat"); 14  writeFile.open(QIODevice::WriteOnly); 15     QDataStream out(&writeFile); 16     out.writeRawData((char *)&aa, sizeof(int)); 17     out.writeRawData((char *)&b, sizeof(char)); 18     out.writeRawData((char *)&c, sizeof(double)); 19  writeFile.close(); 20 
    //读文件
    QFile readFile("1.dat"); 23  readFile.open(QIODevice::ReadOnly); 24     QDataStream in(&readFile); 25     char bf[100]; 26     in.readRawData((char *)&bf, sizeof(int) + sizeof(char) + sizeof(double)); 27  readFile.close(); 28 
    memcpy(&aa, bf, sizeof(int)); 30     memcpy(&b, bf + 4, sizeof(char)); 31     memcpy(&c, bf + 5, sizeof(double)); 32     qDebug() << aa << b << c; 33 
    return 0; 35     return a.exec(); 36 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>

int main(int argc, char *argv[])  7 {  8  QApplication a(argc, argv);  9 
    //写文件
    int aa = 1; 12     char b = 'c'; 13     double c = 2; 14     QFile writeFile("1.dat"); 15  writeFile.open(QIODevice::WriteOnly); 16     QDataStream out(&writeFile); 17     out.writeRawData((char *)&aa, sizeof(int)); 18     out.writeRawData((char *)&b, sizeof(char)); 19     out.writeRawData((char *)&c, sizeof(double)); 20  writeFile.close(); 21 

    //读文件
    QFile readFile("1.dat"); 25  readFile.open(QIODevice::ReadOnly); 26  QByteArray by; 27     char *bf; 28     by = readFile.readAll(); 29     bf = by.data(); 30  readFile.close(); 31 
    memcpy(&aa, bf, sizeof(int)); 33     memcpy(&b, bf + 4, sizeof(char)); 34     memcpy(&c, bf + 5, sizeof(double)); 35     qDebug() << aa << b << c; 36 
    return 0; 38     return a.exec(); 39 }

运行结果：

int main(int argc, char *argv[])  2 {  3  QApplication a(argc, argv);  4 
    //写文件
    int aa = 1;  7     char b = 'c';  8     double c = 2;  9     QFile writeFile("1.dat"); 10  writeFile.open(QIODevice::WriteOnly); 11     QDataStream out(&writeFile); 12     char bbf[100]; 13     char *p; 14     p = (char *)&aa; 15     bbf[0] = p[0]; 16     bbf[1] = p[1]; 17     bbf[2] = p[2]; 18     bbf[3] = p[3]; 19     p = (char *)&b; 20     bbf[4] = p[0]; 21     p = (char *)&c; 22     bbf[5] = p[0]; 23     bbf[6] = p[1]; 24     bbf[7] = p[2]; 25     bbf[8] = p[3]; 26     bbf[9] = p[4]; 27     bbf[10] = p[5]; 28     bbf[11] = p[6]; 29     bbf[12] = p[7]; 30 
    out.writeRawData(bbf, 13); 32  writeFile.close(); 33 

    //读文件
    QFile readFile("1.dat"); 37  readFile.open(QIODevice::ReadOnly); 38  QByteArray by; 39     char *bf; 40     by = readFile.readAll(); 41     bf = by.data(); 42  readFile.close(); 43 
    memcpy(&aa, bf, 4); 45     memcpy(&b, bf + 4, 1); 46     memcpy(&c, bf + 5, 8); 47     qDebug() << aa << b << c; 48 
    return 0; 50     return a.exec(); 51 }

运行结果：

#include "mainwindow.h"
#include <QApplication>
#include <QFile>
#include <QDebug>

int main(int argc, char *argv[])  7 {  8  QApplication a(argc, argv);  9 
    //写文件
    int aa = 1; 12     char b = 'c'; 13     double c = 2; 14     int d = (int)c; 15     QFile writeFile("1.dat"); 16  writeFile.open(QIODevice::WriteOnly); 17     QDataStream out(&writeFile); 18     char bbf[100]; 19     char *p; 20     p = (char *)&aa; 21     bbf[0] = p[0]; 22     bbf[1] = p[1]; 23     bbf[2] = p[2]; 24     bbf[3] = p[3]; 25     p = (char *)&b; 26     bbf[4] = p[0]; 27     p = (char *)&d; 28     bbf[5] = p[0]; 29     bbf[6] = p[1]; 30     bbf[7] = p[2]; 31     bbf[8] = p[3]; 32 
    out.writeRawData(bbf, 9); 34  writeFile.close(); 35 

    //读文件
    QFile readFile("1.dat"); 39  readFile.open(QIODevice::ReadOnly); 40  QByteArray by; 41     char *bf; 42     by = readFile.readAll(); 43     bf = by.data(); 44  readFile.close(); 45 
    int cc; 47     memcpy(&aa, bf, 4); 48     memcpy(&b, bf + 4, 1); 49     memcpy(&cc, bf + 5, 4); 50     qDebug() << aa << b << cc; 51 
    return 0; 53     return a.exec(); 54 }

运行结果：