Open File Dialog Help

["BumbleBee"]

So,this is what I have now:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QDialog>
#include <QPushButton>
#include <QString>
#include <QFileDialog>
#include <QLineEdit>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QLabel>
#include <QTextEdit>
 
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    QPushButton * btn;
    QLineEdit * line;
    QVBoxLayout * layout;
    QHBoxLayout * cl;
    QString * fname;
    QWidget * win;
    QLabel * label;
    QTextEdit * txt;
private slots:
    void open();
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QDialog>
#include <QPushButton>
#include <QString>
#include <QFileDialog>
#include <QLineEdit>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QLabel>
#include <QTextEdit>

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    QPushButton * btn;
    QLineEdit * line;
    QVBoxLayout * layout;
    QHBoxLayout * cl;
    QString * fname;
    QWidget * win;
    QLabel * label;
    QTextEdit * txt;
private slots:
    void open();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

To copy to clipboard, switch view to plain text mode 

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
#include <QFileDialog>
#include <QVBoxLayout>
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    win = new QWidget;
    btn = new QPushButton("Open!",this);
    fname = new QString;
    layout = new QVBoxLayout;
    cl = new QHBoxLayout;
    line = new QLineEdit(this);
    label = new QLabel("Directory",this);
    txt = new QTextEdit;
 
    line->show();
    btn->show();
    txt->show();
 
    layout->addWidget(btn);
    layout->addLayout(cl);
    cl->addWidget(label);
    cl->addWidget(line);
    layout->addWidget(txt);
    win->setLayout(layout);
    MainWindow::setCentralWidget(win);
 
    setFixedHeight(sizeHint().height());
    MainWindow::setWindowTitle("Hello Qt!");
 
    QObject::connect(btn, SIGNAL(clicked()), this, SLOT(open()));
}
 
MainWindow::~MainWindow()
{
    delete ui;
 
}
 
void MainWindow::open()
{
    QFileDialog * fd = new QFileDialog;
    line->setText(fd->getOpenFileName(this));
    //QFile * file = new QFile;  Here error starts...
    //txt->setPlainText(file->read(fd->FileName)); this doesn't work.
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
#include <QFileDialog>
#include <QVBoxLayout>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    win = new QWidget;
    btn = new QPushButton("Open!",this);
    fname = new QString;
    layout = new QVBoxLayout;
    cl = new QHBoxLayout;
    line = new QLineEdit(this);
    label = new QLabel("Directory",this);
    txt = new QTextEdit;

    line->show();
    btn->show();
    txt->show();

    layout->addWidget(btn);
    layout->addLayout(cl);
    cl->addWidget(label);
    cl->addWidget(line);
    layout->addWidget(txt);
    win->setLayout(layout);
    MainWindow::setCentralWidget(win);

    setFixedHeight(sizeHint().height());
    MainWindow::setWindowTitle("Hello Qt!");

    QObject::connect(btn, SIGNAL(clicked()), this, SLOT(open()));
}

MainWindow::~MainWindow()
{
    delete ui;

}

void MainWindow::open()
{
    QFileDialog * fd = new QFileDialog;
    line->setText(fd->getOpenFileName(this));
    //QFile * file = new QFile;  Here error starts...
    //txt->setPlainText(file->read(fd->FileName)); this doesn't work.
}

To copy to clipboard, switch view to plain text mode 

All is ok except the last 2 lines...I don't know how to open and read content with QFile.

[ars]

What about reading QFile documentation and your compiler error messages?

Here´s some more or less pseudo code for your open() slot:

void MainWindow::open()
{
   QString fname = QFileDialog::getOpenFileName(this, tr("Put your dialog caption here"));
   QFile openFile(fname); // you may check for fname.isEmpty before
   openFile.open(QIODevice::ReadOnly); // you should do some error checking here!
   QByteArray content = openFile.readAll(); 
   txt->setPlainText(QString(content));
}

void MainWindow::open()
{
   QString fname = QFileDialog::getOpenFileName(this, tr("Put your dialog caption here"));
   QFile openFile(fname); // you may check for fname.isEmpty before
   openFile.open(QIODevice::ReadOnly); // you should do some error checking here!
   QByteArray content = openFile.readAll(); 
   txt->setPlainText(QString(content));
}

To copy to clipboard, switch view to plain text mode 

If you don't find the methods you're looking for in the documentation of a class, you may also look into the documentation of its parent class. In the code snippet above, readAll() e.g. is documented in class QIODevice, the parent class of QFile.

[squidge]

Is there a reason you are both initialising the UI (ui.setupUI) and creating your own widgets? As stated previously, you would normally let the setupUI create all your widgets for you, and if you don't want that, you would remove the references to the UI namespace.