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Thread: Read values from text file and display it in lineditbox

  1. #1
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    Default 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:n_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!!

  2. #2
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    Default Re: Read values from text file and display it in lineditbox

    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

  3. The following user says thank you to aamer4yu for this useful post:

    kulsekarr (26th June 2012)

  4. #3
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    Default Re: Read values from text file and display it in lineditbox

    See this code:------>

    widget.h
    Qt Code:
    1. #ifndef WIDGET_H
    2. #define WIDGET_H
    3.  
    4. #include <QWidget>
    5. #include<QFile>
    6. #include<QString>
    7.  
    8. namespace Ui {
    9. class Widget;
    10. }
    11.  
    12. class Widget : public QWidget
    13. {
    14. Q_OBJECT
    15.  
    16. public:
    17. explicit Widget(QWidget *parent = 0);
    18. ~Widget();
    19.  
    20. public slots:
    21. void updating();
    22.  
    23. private:
    24. Ui::Widget *ui;
    25. QFile *file;
    26. QString str;
    27. };
    28.  
    29. #endif // WIDGET_H
    To copy to clipboard, switch view to plain text mode 

    widget.cpp
    Qt Code:
    1. #include "widget.h"
    2. #include "ui_widget.h"
    3. #include<QTextStream>
    4.  
    5. Widget::Widget(QWidget *parent) :
    6. QWidget(parent),
    7. ui(new Ui::Widget)
    8. {
    9. ui->setupUi(this);
    10. file=new QFile("demo.txt");
    11. if(file->open(QIODevice::ReadOnly)){
    12. QTextStream stream(file);
    13. str=stream.readAll();
    14. }
    15. connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(updating()));
    16. }
    17.  
    18. void Widget::updating(){
    19. ui->lineEdit->setText(str);
    20. }
    21.  
    22. Widget::~Widget()
    23. {
    24. delete ui;
    25. }
    To copy to clipboard, switch view to plain text mode 

  5. The following user says thank you to sonulohani for this useful post:

    kulsekarr (26th June 2012)

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    Default Re: Read values from text file and display it in lineditbox

    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.
    Last edited by kulsekarr; 26th June 2012 at 15:05. Reason: updated contents

  7. #5
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    Default Re: Read values from text file and display it in lineditbox

    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..
    Attached Files Attached Files

  8. #6
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    Default Re: Read values from text file and display it in lineditbox

    See this example ---->


    I think you will now figure out....

    untitled1.zip
    Last edited by sonulohani; 27th June 2012 at 09:59.

  9. The following user says thank you to sonulohani for this useful post:

    kulsekarr (27th June 2012)

  10. #7
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    Default Re: Read values from text file and display it in lineditbox

    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...

  11. #8
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    Cool Re: Read values from text file and display it in lineditbox

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

    Capture.JPGCapture1.JPG

    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

    Qt Code:
    1. ui->setupUi(this);
    2. //QString str; //Comment this.
    3. QFile file("sp.txt");
    4. if(file.open(QIODevice::ReadOnly))
    5. {
    6. QTextStream stream(&file);
    7. stream >> str;
    8. file.close();
    9. }
    To copy to clipboard, switch view to plain text mode 
    Last edited by sonulohani; 27th June 2012 at 12:26.

  12. The following user says thank you to sonulohani for this useful post:

    kulsekarr (27th June 2012)

  13. #9
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    Default Re: Read values from text file and display it in lineditbox

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

  14. #10
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    Default Re: Read values from text file and display it in lineditbox

    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?

    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!
    ==========================signature=============== ==================
    S.O.L.I.D principles (use them!):
    https://en.wikipedia.org/wiki/SOLID_...iented_design)

    Do you write clean code? - if you are TDD'ing then maybe, if not, your not writing clean code.

  15. The following user says thank you to high_flyer for this useful post:

    kulsekarr (28th June 2012)

  16. #11
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    Cool Re: Read values from text file and display it in lineditbox

    Check This:---->

    Your working project---->

    Widget(1).zip

  17. The following user says thank you to sonulohani for this useful post:

    kulsekarr (28th June 2012)

  18. #12
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    Default Re: Read values from text file and display it in lineditbox

    try with
    Qt Code:
    1. file.open(QIODevice::readonly | QIODevice::text)
    To copy to clipboard, switch view to plain text mode 
    and use qtextstream to exract data
    Life is about making the right decisions and moving on.

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