Read values from text file and display it in lineditbox

Hi,
I am trying to read values from a text file and make it to display in the lineEdit box, i have used the code below but it is not working out.


void MainWindow::on_start_clicked()
{
QString str;
QFile file("sp.txt");
if (!file.open(QIODevice::ReadOnly))
{
QTextStream in(&file);
in >> str;
file.close();
}

ui->lineEdit->setText(str); // this is for displaying the values in the line edit box
}


i have also used this connect function in the constructor
connect(ui->start,SIGNAL(clicked()),this,SLOT(on_start_clicke d()));

start is the object name of the push button..
i have also included the header QtextStream

The text file contains values as
23
34
44

kindly do please help me out!!

if (!file.open(QIODevice::ReadOnly))

There shouldn't be negation.. The if code is not executing !!

Also you can use file.readAll() to read all the text :)

See this code:------>

widget.h

Code:

---

#ifndef WIDGET_H
#define WIDGET_H
 
#include <QWidget>
#include<QFile>
#include<QString>
 
namespace Ui {
class Widget;
}
 
class Widget : public QWidget
{
    Q_OBJECT
 
public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();
 
public slots:
    void updating();
 
private:
    Ui::Widget *ui;
    QFile *file;
    QString str;
};
 
#endif // WIDGET_H

---

widget.cpp

Code:

---

#include "widget.h"
#include "ui_widget.h"
#include<QTextStream>
 
Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    file=new QFile("demo.txt");
    if(file->open(QIODevice::ReadOnly)){
        QTextStream stream(file);
        str=stream.readAll();
    }
    connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(updating()));
}
 
void Widget::updating(){
    ui->lineEdit->setText(str);
}
 
Widget::~Widget()
{
    delete ui;
}

---

Thank you very much for your reply ! if i run the above code it is showing exited with 0, and it is not displaying in the line edit box.

Hi any one please help me out in displaying the values that are read from the text file and still it is not displaying in the line edit box. I have attached my application kindly do check it. any reply is appreciated its urgent.. please..

See this example ---->


I think you will now figure out....

Attachment 7903

Thank you for your reply but still i am facing that same problem wit the sample code that u have sent it to me help me...

It is working fine in my computer:-
You can see the output------>

Attachment 7907Attachment 7908

Copy the source code and paste that in the new project.....

---

Added after 11 minutes:

I am making changes in your widget.zip file. Wait for some time.

---

Added after 6 minutes:

Hey,

Make this change in your project

Code:

---

ui->setupUi(this);
    //QString str;                   //Comment this.
    QFile file("sp.txt");
    if(file.open(QIODevice::ReadOnly))
      {
        QTextStream stream(&file);
        stream >> str;
        file.close();
    }

---

i Have made the changes as you said but still not working....what will be problem?

You could help your self and those who try to help you by showing some initiative and TRY to work the problem you self, and produce as much information regarding what you have tried and what results you got.
The problem could be ANYTHING.
To reduce it from anything to just few things debugging is needed.
Therefore, debug your application.
Run it in a debugger, and step through.
Then you can answer the following questions:
1. Does the file get opened?
2. If 1 is true, is the data being read ok by the stream?
3. if 2 is true, is the slot being fired?

Quote:

---

i Have made the changes as you said but still not working....what will be problem?

---

Did you notice that your 'str' variable was a local and the previous posters have changed it to a member?
Did you copy the suggested files or did you copy the code?
Make sure you work with the code you got!

Check This:---->

Your working project---->

Attachment 7909

try with

Code:

---

file.open(QIODevice::readonly | QIODevice::text)

---

and use qtextstream to exract data