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;
}


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




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();
}



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.