QT memory mapping

Hello everyone , I meet you again , I'm your friend, Quan Jun .

Recently, when looking at the code, I found Qt Memory mapping for , I only know MFC There is a memory mapping mechanism , You can save time when reading big data files , original Qt There are corresponding mechanisms in , Its usage is simpler , Here is a small example to demonstrate its usage

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QDebug>
#include <iostream>
#include <stdio.h>
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QFile file("1.txt");
    file.open(QIODevice::ReadWrite);
    qDebug() << QStringLiteral(" Memory size ：") << file.size();
    uchar *fpr = file.map(0, file.size());
    int i = 0;
    int x1 = 0, x2 = 0, x3 = 0;
    char *pEnd1 = NULL;
    char *pEnd2 = NULL;
    char *pEnd3 = (char *)fpr;
    for (int i = 0 ; i < 3 ; ++i)
    {
        x1 = strtod(pEnd3, &pEnd1);
        x2 = strtod(pEnd1, &pEnd2);
        x3 = strtod(pEnd2, &pEnd3);

        std::cout << x1 << "," << x2 << "," << x3 << "\n";
    }

    file.close();
    return a.exec();
}

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