Output problem

[aegis]

hi, i am reading this book on qt4::: An Introduction to Design Patterns in C++ with Qt4

one of the examples has the following code:

qtio-demo.cpp

#include <QDate>
#include <QFile>
#include "qstd.h"
//start
int main() {
    using namespace qstd;
    QDate d1(2002, 4,1), d2(QDate::currentDate());
    int days;
    cout << "The first date is: " << d1.toString()
            << "\nToday's date is: "
            << d2.toString("ddd MMMM d, yyyy")<< endl;
 
    if (d1 <  d2)
        cout << d1.toString("MM/dd/yy") << " is earlier than "
                << d2.toString("yyyyMMdd") << endl;
 
    cout << "There are " << d1.daysTo(d2)
            << " days between "
            << d1.toString("MMM dd, yyyy") << " and "
            << d2.toString(Qt::ISODate)  << endl;
 
    cout << "Enter number of days to add to the first date: "
            <<  flush;
    days = promptInt();
    cout << "The first date was " << d1.toString()
            << "\nThe computed date is "
            <<  d1.addDays(days).toString() << endl;
    cout << "First date displayed in longer format: "
            << d1.toString("dddd, MMMM dd, yyyy")  << endl;
//end
 
   cout << "\nNow we save the following dates to a file: \n"
           << d1 .toString() << '\t' << d2.toString() << endl;
    QFile outfile;
    promptOutputFile(outfile);
    QTextStream ofs (&outfile);
     ofs << d1.toString() << '\n';
     ofs << d2.toString() << '\n';
     outfile.flush();
     outfile.close();
     cout << "Now we read those dates from the file:\n";
     QFile infile;
     promptInputFile(infile);
     QTextStream ifstr(&infile);
     QString dateStr;
     QDate dt1, dt2;          // we use new variables
     dateStr = ifstr.readLine();
     dt1 = QDate::fromString(dateStr);
     dateStr = ifstr.readLine();
     dt2 = QDate::fromString(dateStr);
     cout << "Here are the dates we read from the file:\n"
             << dt1.toString() << '\n'
             << dt2.toString() <<  endl;
      infile.close();
      return 0;
}

#include <QDate>
#include <QFile>
#include "qstd.h"
//start
int main() {
    using namespace qstd;
    QDate d1(2002, 4,1), d2(QDate::currentDate());
    int days;
    cout << "The first date is: " << d1.toString()
            << "\nToday's date is: "
            << d2.toString("ddd MMMM d, yyyy")<< endl;

    if (d1 <  d2)
        cout << d1.toString("MM/dd/yy") << " is earlier than "
                << d2.toString("yyyyMMdd") << endl;

    cout << "There are " << d1.daysTo(d2)
            << " days between "
            << d1.toString("MMM dd, yyyy") << " and "
            << d2.toString(Qt::ISODate)  << endl;

    cout << "Enter number of days to add to the first date: "
            <<  flush;
    days = promptInt();
    cout << "The first date was " << d1.toString()
            << "\nThe computed date is "
            <<  d1.addDays(days).toString() << endl;
    cout << "First date displayed in longer format: "
            << d1.toString("dddd, MMMM dd, yyyy")  << endl;
//end

   cout << "\nNow we save the following dates to a file: \n"
           << d1 .toString() << '\t' << d2.toString() << endl;
    QFile outfile;
    promptOutputFile(outfile);
    QTextStream ofs (&outfile);
     ofs << d1.toString() << '\n';
     ofs << d2.toString() << '\n';
     outfile.flush();
     outfile.close();
     cout << "Now we read those dates from the file:\n";
     QFile infile;
     promptInputFile(infile);
     QTextStream ifstr(&infile);
     QString dateStr;
     QDate dt1, dt2;          // we use new variables
     dateStr = ifstr.readLine();
     dt1 = QDate::fromString(dateStr);
     dateStr = ifstr.readLine();
     dt2 = QDate::fromString(dateStr);
     cout << "Here are the dates we read from the file:\n"
             << dt1.toString() << '\n'
             << dt2.toString() <<  endl;
      infile.close();
      return 0;
}

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qstd.h

#ifndef QSTD_H
#define QSTD_H
 
#include <QTextStream>
#include <QFile>
#include <QString>
 
/** @short helper objects and functions which help reduce the
       need for char[] and the standard library.  
 
    defines three @ref QTextStream instances
    which behave like the c++ standard iostreams, bound to the
    standard in/out/error. 
    
    Also provided, some helper functions for writing
    interactive stdin/stdout applications.
*/
//start
namespace qstd {
 
    /** @short  An alias for standard input
     */
    extern QTextStream cin;  /* declared only, defined in the .cpp file */
    /** @short  An alias for standard output
     */
    extern QTextStream cout;
    /** @short  An alias for standard error
     */
    extern QTextStream cerr;
    /** yes/no prompt
        interactive stdin UI - prompts user with
        a yes/no question. Repeatedly-asks
        until user supplies a valid answer.
 
        @param yesNoQuestion the yes/no question
        @return true/false depending on what the
        user responded.
    */
    bool yes(QString yesNoQuestion);
    /** Convenience function that feeds a  specific question
        to the yes() function.
        @usage do {.....} while(more ("foobar"));
        so that user sees the question: "Another foobar (y/n)? "
        @param name of the item being handled by the loop.
    */
    bool more(QString prompt);
    /** A function for safely taking an int from the keyboard.
        Takes data into a  QString and tests to make sure it
        can be converted to int before returning.
        @param base allows choice of number base.
        @return returns validated int.
    */
    int promptInt(int base = 10);
    /** A function for safely taking a double from the keyboard.
        Takes data into a  QString and tests to make sure it
        can be converted to double before returning.
        @return returns validated int.
    */
    double promptDouble();
    /** Complete dialog for opening a file for output.
        Asks user for file name, checks to see if
        file already exists and, if so, asks the user if
        it is ok to overwrite.
        @param Reference QFile parameter is set to point
        to the (eventually) opened file.
    */
    /** @short Dialog for a output file prompt
     */
    void promptOutputFile(QFile& outfile);
 
    /** @short Dialog for input file prompt */
    void promptInputFile(QFile& infile);
 
 
//end
}
 
#endif

#ifndef QSTD_H
#define QSTD_H

#include <QTextStream>
#include <QFile>
#include <QString>

/** @short helper objects and functions which help reduce the
       need for char[] and the standard library.  

    defines three @ref QTextStream instances
    which behave like the c++ standard iostreams, bound to the
    standard in/out/error. 
    
    Also provided, some helper functions for writing
    interactive stdin/stdout applications.
*/
//start
namespace qstd {

    /** @short  An alias for standard input
     */
    extern QTextStream cin;  /* declared only, defined in the .cpp file */
    /** @short  An alias for standard output
     */
    extern QTextStream cout;
    /** @short  An alias for standard error
     */
    extern QTextStream cerr;
    /** yes/no prompt
        interactive stdin UI - prompts user with
        a yes/no question. Repeatedly-asks
        until user supplies a valid answer.
 
        @param yesNoQuestion the yes/no question
        @return true/false depending on what the
        user responded.
    */
    bool yes(QString yesNoQuestion);
    /** Convenience function that feeds a  specific question
        to the yes() function.
        @usage do {.....} while(more ("foobar"));
        so that user sees the question: "Another foobar (y/n)? "
        @param name of the item being handled by the loop.
    */
    bool more(QString prompt);
    /** A function for safely taking an int from the keyboard.
        Takes data into a  QString and tests to make sure it
        can be converted to int before returning.
        @param base allows choice of number base.
        @return returns validated int.
    */
    int promptInt(int base = 10);
    /** A function for safely taking a double from the keyboard.
        Takes data into a  QString and tests to make sure it
        can be converted to double before returning.
        @return returns validated int.
    */
    double promptDouble();
    /** Complete dialog for opening a file for output.
        Asks user for file name, checks to see if
        file already exists and, if so, asks the user if
        it is ok to overwrite.
        @param Reference QFile parameter is set to point
        to the (eventually) opened file.
    */
    /** @short Dialog for a output file prompt
     */
    void promptOutputFile(QFile& outfile);

    /** @short Dialog for input file prompt */
    void promptInputFile(QFile& infile);
    
    
//end
}

#endif

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qstd.cpp

//start id=namespace
#include "qstd.h"
 
/* QTextStreams look a lot like iostreams,
we just have to point them to the right place. */
 
//start id=streamdefs
QTextStream qstd::cin(stdin, QIODevice::ReadOnly);
QTextStream qstd::cout(stdout, QIODevice::WriteOnly);
QTextStream qstd::cerr(stderr, QIODevice::WriteOnly);
//end
 
 
/* Namespace members are like static class members */
bool qstd::yes(QString question) {
    QString ans;
    cout << QString(" %1 [y/n]? ").arg(question);
    cout.flush();
    ans = cin.readLine();
    return (ans.toUpper().startsWith("Y", Qt::CaseInsensitive));
}
//end
 
bool qstd::more(QString s) {
    return yes(QString("Another %1").arg(s));
}
 
 
int qstd::promptInt(int base /* =10 */) { /* Usage: int n = promptInt(); */
    QString numstr;
    int result;
    bool ok;
    cout << ": " << flush;
    while (1) {
        numstr = cin.readLine();
        result = numstr.toInt(&ok, base);
        if (!ok) {
            cout << "Invalid number. Try again: ";
            cout.flush();
        }
        else
            return result;
    }
}
 
 
double qstd::promptDouble() { /* Usage: double d = promptDouble(); */
    QString numstr;
    double result;
    bool ok;
    while (1) {
        numstr = cin.readLine();
        result = numstr.toDouble(&ok);
        if (!ok) {
            cout << "Invalid number. Try again: ";
            cout.flush();
        }
        else
            return result;
    }
}
 
 
void qstd::promptOutputFile(QFile& outfile) {
    QString filename;
    while (1) {
        cout << "Please enter the file name for saving this data: ";
        cout.flush();
        filename = cin.readLine();
        outfile.setFileName(filename);
        bool fileExists = outfile.open(QIODevice::ReadOnly);
        if (!fileExists)
            break;
        if (yes("File already exists ... Ok to overwrite"))
            break;
        outfile.close();
        outfile.reset();
    }
    outfile.close();
    outfile.reset();
    outfile.open(QIODevice::WriteOnly);
    cout << filename << " open for writing ...\n";
    cout.flush();
}
 
 
void qstd::promptInputFile(QFile& infile) {
    QString filename;
    while (1) {
        cout << "Name of the file to be read:  ";
        cout.flush();
        filename = cin.readLine();
        infile.setFileName(filename);
        bool fileExists = infile.open(QIODevice::ReadOnly);
        if (fileExists)
            break;
        cout << "File does not exist ... Please try again. \n";
        cout.flush();
        infile.reset();
    }
    cout << filename << " open for reading ...\n";
    cout.flush();
}

//start id=namespace
#include "qstd.h"

/* QTextStreams look a lot like iostreams,
we just have to point them to the right place. */

//start id=streamdefs
QTextStream qstd::cin(stdin, QIODevice::ReadOnly);
QTextStream qstd::cout(stdout, QIODevice::WriteOnly);
QTextStream qstd::cerr(stderr, QIODevice::WriteOnly);
//end


/* Namespace members are like static class members */
bool qstd::yes(QString question) {
    QString ans;
    cout << QString(" %1 [y/n]? ").arg(question);
    cout.flush();
    ans = cin.readLine();
    return (ans.toUpper().startsWith("Y", Qt::CaseInsensitive));
}
//end

bool qstd::more(QString s) {
    return yes(QString("Another %1").arg(s));
}


int qstd::promptInt(int base /* =10 */) { /* Usage: int n = promptInt(); */
    QString numstr;
    int result;
    bool ok;
    cout << ": " << flush;
    while (1) {
        numstr = cin.readLine();
        result = numstr.toInt(&ok, base);
        if (!ok) {
            cout << "Invalid number. Try again: ";
            cout.flush();
        }
        else
            return result;
    }
}


double qstd::promptDouble() { /* Usage: double d = promptDouble(); */
    QString numstr;
    double result;
    bool ok;
    while (1) {
        numstr = cin.readLine();
        result = numstr.toDouble(&ok);
        if (!ok) {
            cout << "Invalid number. Try again: ";
            cout.flush();
        }
        else
            return result;
    }
}


void qstd::promptOutputFile(QFile& outfile) {
    QString filename;
    while (1) {
        cout << "Please enter the file name for saving this data: ";
        cout.flush();
        filename = cin.readLine();
        outfile.setFileName(filename);
        bool fileExists = outfile.open(QIODevice::ReadOnly);
        if (!fileExists)
            break;
        if (yes("File already exists ... Ok to overwrite"))
            break;
        outfile.close();
        outfile.reset();
    }
    outfile.close();
    outfile.reset();
    outfile.open(QIODevice::WriteOnly);
    cout << filename << " open for writing ...\n";
    cout.flush();
}


void qstd::promptInputFile(QFile& infile) {
    QString filename;
    while (1) {
        cout << "Name of the file to be read:  ";
        cout.flush();
        filename = cin.readLine();
        infile.setFileName(filename);
        bool fileExists = infile.open(QIODevice::ReadOnly);
        if (fileExists)
            break;
        cout << "File does not exist ... Please try again. \n";
        cout.flush();
        infile.reset();
    }
    cout << filename << " open for reading ...\n";
    cout.flush();
}

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the code compiles without any problems or errors.The thing is that the application created does nothing!!!!
it doesn't take input and it doesn't give output...

How can i fix this??
I just want to use some of qt's classes and output to console...

PS: i am developing on Windows environment{if it matters..}

thanks for your time,
Nicolas

[wysota]

Add CONFIG+=console to your project file and rerun qmake.

[vfernandez]

I don't have much experience with Qt on Windows but perhaps the program is being detached from the terminal. Have you tried a simple printf() to check if it's being detached?

[aegis]

Add CONFIG+=console to your project file and rerun qmake.

i did so, and it worked!!! BUT it doesn't display the date correctly{unknown letters appear....maybe because the local is greek??}and it doesn't accept input correctly.....
what can be done??

secondly to create the project file i run qmake -project....shouldn't this add by itself the CONFIG+=console ????

thanks for your time

[wysota]

BUT it doesn't display the date correctly{unknown letters appear....maybe because the local is greek??}and it doesn't accept input correctly.....
what can be done??

You can set a QTextCodec.

shouldn't this add by itself the CONFIG+=console ????

No, why should it? Not every application needs access to the console.