file operations

[prathibha83]

Hi,

I am trying sample File read and write operations.My code is able to create a file and writing some text into it.but reading is not working properly.my code is as follows...



#include "FileEx.h"
#include <QFile>
#include <QLabel>
#include <QDataStream>
#include<QTextStream>
FileEx::FileEx(QWidget *parent)
: QWidget(parent)
{
QFile file("c://test.txt");
file.open(QIODevice::WriteOnly);
QDataStream out(&file); // we will serialize the data into the file
out << "welcome to the Qt World"; // serialize a string
file.close();
QFile read("c://test.txt");
read.open(QIODevice::ReadOnly | QIODevice::Text);
//QDataStream in(&read);
// read the data serialized from the file

QTextStream in(&read);
QString line = QString(in.readLine());
QLabel *label = new QLabel(line);
//label->setText(line);
label->show();



/*QString str;
in >> str;
QLabel *label = new QLabel;
label->setText(str);
label->show(); */
}

FileEx::~FileEx()
{

}

[divanov]

Try this test application:

#include <QtGui>

int main (int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    QFile file("test.txt");
    if(!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
       qDebug("IO error");
       return 1;
    }
    QTextStream out(&file);
    out << "welcome to the Qt World";
    file.close();

    QFile read("test.txt");
    if(!read.open(QIODevice::ReadOnly | QIODevice::Text)) {
       qDebug("IO error");
       return 2;
    }
    QTextStream in(&read);
    QString line = in.readLine();
    qDebug() << line;
    read.close();
}

[prathibha83]

thaks for the reply....

I tried with u r code...but nothing appears on the screen.

[divanov]

thaks for the reply....

I tried with u r code...but nothing appears on the screen.

Because it's a console application.

[prathibha83]

Thanks....its working fine....

[prathibha83]

if I want to see the o/p on the emulator how can I do it....
please help me.

[divanov]

#include <QtGui>

int main (int argc, char **argv)
{
    QApplication app(argc, argv);

    QFile file("test.txt");
    if(!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
       qDebug("IO error");
       return 1;
    }
    QTextStream out(&file);
    out << "welcome to the Qt World";
    file.close();

    QFile read("test.txt");
    if(!read.open(QIODevice::ReadOnly | QIODevice::Text)) {
       qDebug("IO error");
       return 2;
    }
    QTextStream in(&read);
    QString line = in.readLine();
    read.close();

    QLabel label;
    label.setText(line);
    label.setAlignment(Qt::AlignCenter);
    label.showMaximized();

    return app.exec();
}