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Revman 12-07-2003 07:46 PM

Homework Help
 
I'm having problems opening and reading from a file to test a Class.

My diver main.cpp is fairly short but with a longer file open function

// Project #4 -- Main/driver program


#include "daytime.h"
#include <string>
#include <fstream>
#include <iostream>

using namespace std;

void openFile (ifstream&);


int main()
{

DayTime Day1, Day2;

ifstream file;

openFile(file);

//DEBUG: test read from the file

int one, two, three;

file >> one >> two >> three;

cout << one << two << three << endl;

//DEBUG END!

Day1 >> file;

Day2 >> file;


// Watch -- not intutitive.
Day1 << Day2;

Day2 << Day1;

return 0;
};



//************************************************** ************************
*******
// openFile Function
//************************************************** ************************
*******

// Precondition:
// recieves inputstream

// Postcondition:

// Verifies user identified file exists, reprompts if necessary.
// opens the file

void openFile(/* in/out */ ifstream& anyFile)

{
string fileName;

int choice = 0;

// used to test if the file was opened suscessfully
int test;

do
{
test = 0; // assume file will be opened correctly

do
{
cout << "Enter the name of the file to open." << endl;

cin >> fileName;

//Prompt for standard file extension(s), if omitted.
cout << endl << "Choose the type of file to open." << endl;

cout << "1 = TXT" << endl << "2 = DAT" << endl;

cout << "3 = Entered file type with file name" << endl;

cin >> choice;

if (choice < 1 || choice > 3)
{
cout << "Error with file type selection." << endl;

cout << "Restarting open file process" << endl;
}
}
while (choice < 1 && choice > 3);

// add file name extension, if required
switch (choice)
{
case 1 : fileName = fileName + ".txt";
break;

case 2 : fileName = fileName + ".dat";
break;

default: break; // no action necessary already included
};

//try to open the file
anyFile.open(fileName.c_str());

cout << "Attempting to open file" << endl;

if (!anyFile)
{
cout << "Error opening file" << endl;

test = 1;

anyFile.clear();
}

}
while(test == 1);

cout << "File open suscessfully" << endl;

return;
}


My class slecification file has some overloaded operators, required by the
project, is as follows:

//************************************************** ********
//*** This is the decelaration file for the daytime class***
//*** Specifications can be found in the daytime.cpp file***
//************************************************** ********

#include<fstream>

using namespace std;

class DayTime
{
public:
DayTime(); // default constructor

// used to extract day hour minute to the class private members
void operator>> (/* in */ ifstream& anyFile);


void operator << (DayTime otherDayTime);
// used to output to screen the dayTime


// use to compare see if two insitances of DayTime are equal
bool operator == (DayTime otherDayTime);

// used to determine of one DayTime is less than another DayTime
// Assumes Sunday< Monday< Tuesday< ... < Saturday
bool operator < (DayTime otherDayTime);

private:
enum days {ERROR, Sun, Mon, Tue, Wen, Thu, Fri, Sat} day;

int hour;

int min;
};

The implemation file is as follows:

//************************************************** ************************
*******
//*** This is theimplementation file of DayTime class
//************************************************** ************************
*******

#include "daytime.h"
#include <iostream>

using namespace std;

// private members of class

// enum days {ERROR, Sun, Mon, Tues, Wen, Thu, Fri, Sat} day;

// int hour;

// int min;

//Class declrations

//************************************************** ************************
*******

DayTime::DayTime() // default constructor

// Precondition:
// None

//Postsondition:
// Constructed, day set to ERROR, how and min set to "0"

{

day = ERROR;

hour = 0;

min = 0;

}

//************************************************** ************************
*******

void DayTime::operator>> (/* in */ ifstream& anyFile)

// Precondition:
// stream is in day/hour/min order
//0 < Day < 8 , -1 < Hour < 24 , and -1 < Min < 60

//Postcondition:

// Day, hour, and minute are set

{
int inDay;

int inHour;

int inMin;

anyFile >> inDay >> inHour >> inMin;

//debug statement
cout << inDay << inHour << inMin;

switch (inDay) // use inDay to set enum day
{
case 1 : day = Sun;

break;

case 2: day = Mon;

break;

case 3: day = Tue;

break;

case 4: day = Wen;

break;

case 5: day = Thu;

break;

case 6: day = Fri;

break;

case 7: day = Sat;

break;

default: cout << "Error!" << endl;

break;
}

hour = inHour;

min = inMin;
}

//************************************************** ************************
*******

void DayTime::operator<<(DayTime otherDayTime)

//Precondition:
// DayTime has been set

//Postcondition:
// private members are displayed to the screen in

// DDD HH:MM 'endl'
//format

{
cout << day << " ";

if (hour < 10)

cout << "0";

cout << hour << ":";

if (min < 10)

cout << "0";

cout << min << endl;

}

//************************************************** ************************
*******

bool DayTime::operator==(/* in */ DayTime otherDayTime)

//Precondition:
// Current and otherDayTime are declared

//Postcondition:
// if DayTime == otherDayTime, returns true
// else, returns false

{
return (day == otherDayTime.day &&
hour == otherDayTime.hour &&
min == otherDayTime.min);
}


//************************************************** ************************
*******

bool DayTime::operator <(/* in */ DayTime otherDayTime)

//Precondition:
// Current and otherDayTime are declared

//Postcondition:
// if DayTime < otherDayTime, returns true
// else, returns false

{
if (day < otherDayTime.day)
return true;

if (day == otherDayTime.day &&
hour < otherDayTime.hour)

return true;

if (day == otherDayTime.day &&
hour == otherDayTime.hour &&
min <otherDayTime.min)

return true;

return false;
}

What I recieve as output when debugging these files I get the following as
output:


Enter the name of the file to open.

Choose the type of file to open.

1 = TXT

2 = DAT

3 = Entered file type with file name

Attempting to open file

File open suscessfully

15-858993460

-858993460-858993460-858993460Error!

-858993460-858993460-858993460Error!

0 0-858993460:0-858993460

0 0-858993460:0-858993460



Any help is greately appericated.

Revman




Jack Klein 12-08-2003 04:53 AM

Re: Homework Help
 
On Sun, 7 Dec 2003 13:46:29 -0600, "Revman" <Revman@cox.net> wrote in
comp.lang.c++:

> I'm having problems opening and reading from a file to test a Class.
>
> My diver main.cpp is fairly short but with a longer file open function


First problem, you posted way too much code. Did you type all this
without testing it? Do you know how to use the debugger that comes
with your compiler? What have you attempted to find and fix the
problem already?

I'm not going to go through all your code, but I will point out
something that jumped out at me:


> void openFile(/* in/out */ ifstream& anyFile)
>
> {
> string fileName;
>
> int choice = 0;
>
> // used to test if the file was opened suscessfully
> int test;
>
> do
> {
> test = 0; // assume file will be opened correctly
>
> do
> {

[snip]
> }
> while (choice < 1 && choice > 3);


The while expression above will ALWAYS be false. It is impossible for
any value to be both less than 1 AND greater than 3 at the same time.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c++ ftp://snurse-l.org/pub/acllc-c++/faq

Gary Labowitz 12-08-2003 11:38 AM

Re: Homework Help
 
"Jack Klein" <jackklein@spamcop.net> wrote in message
news:8o08tvs5r51ket1562p5mic8e4undkmn49@4ax.com...
> On Sun, 7 Dec 2003 13:46:29 -0600, "Revman" <Revman@cox.net> wrote in
> comp.lang.c++:


> I'm not going to go through all your code, but I will point out
> something that jumped out at me:

<<snip>>
> > while (choice < 1 && choice > 3);

>
> The while expression above will ALWAYS be false. It is impossible for
> any value to be both less than 1 AND greater than 3 at the same time.


Thanks, Jack. This is one of my top 10. For those who didn't think it was
such a big deal, I offer this as an example of the kind of thing that comes
up often in class.
--
Gary



Jack Klein 12-09-2003 04:07 AM

Re: Homework Help
 
On Mon, 8 Dec 2003 06:38:47 -0500, "Gary Labowitz"
<glabowitz@comcast.net> wrote in comp.lang.c++:

> "Jack Klein" <jackklein@spamcop.net> wrote in message
> news:8o08tvs5r51ket1562p5mic8e4undkmn49@4ax.com...
> > On Sun, 7 Dec 2003 13:46:29 -0600, "Revman" <Revman@cox.net> wrote in
> > comp.lang.c++:

>
> > I'm not going to go through all your code, but I will point out
> > something that jumped out at me:

> <<snip>>
> > > while (choice < 1 && choice > 3);

> >
> > The while expression above will ALWAYS be false. It is impossible for
> > any value to be both less than 1 AND greater than 3 at the same time.

>
> Thanks, Jack. This is one of my top 10. For those who didn't think it was
> such a big deal, I offer this as an example of the kind of thing that comes
> up often in class.


Yes, I've never written code like this... today! Of course it just so
happens that I had today off, and didn't go to work.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.learn.c-c++ ftp://snurse-l.org/pub/acllc-c++/faq

Thomas Matthews 12-10-2003 04:32 PM

Re: Homework Help
 
Revman wrote:

> I'm having problems opening and reading from a file to test a Class.
>
> My diver main.cpp is fairly short but with a longer file open function
>
> // Project #4 -- Main/driver program
>
>
> #include "daytime.h"
> #include <string>
> #include <fstream>
> #include <iostream>
>
> using namespace std;
>
> void openFile (ifstream&);
>
>
> int main()
> {
>
> DayTime Day1, Day2;
>
> ifstream file;
>
> openFile(file);
>
> //DEBUG: test read from the file
>
> int one, two, three;
>
> file >> one >> two >> three;
>
> cout << one << two << three << endl;
>
> //DEBUG END!
>
> Day1 >> file;
>
> Day2 >> file;

I'm surprised nobody caught this one!.
You have declared the file as an "ifstream", which
is a read-only stream and yet here you are writing
to it. You need to either open the file as bi-directional
or close it and open it in write mode.


> // Watch -- not intutitive.
> Day1 << Day2;
>
> Day2 << Day1;
>
> return 0;
> };

[snip -- openfile function]


> My class slecification file has some overloaded operators, required by the
> project, is as follows:
>
> //************************************************** ********
> //*** This is the decelaration file for the daytime class***

Spelling: "declaration" or "deceleration". One is to slow down
the other to announce something. Guess which one?


> //*** Specifications can be found in the daytime.cpp file***

Specifications should be in the header file.


> //************************************************** ********
>
> #include<fstream>
>
> using namespace std;
>
> class DayTime
> {
> public:
> DayTime(); // default constructor
>
> // used to extract day hour minute to the class private members
> void operator>> (/* in */ ifstream& anyFile);
>
>
> void operator << (DayTime otherDayTime);
> // used to output to screen the dayTime
>
>
> // use to compare see if two insitances of DayTime are equal
> bool operator == (DayTime otherDayTime);
>
> // used to determine of one DayTime is less than another DayTime
> // Assumes Sunday< Monday< Tuesday< ... < Saturday
> bool operator < (DayTime otherDayTime);
>
> private:
> enum days {ERROR, Sun, Mon, Tue, Wen, Thu, Fri, Sat} day;
>
> int hour;
>
> int min;
> };

If the hour and min variables can be negative then use "int",
otherwise use an "unsigned int". This will allow the compiler
to use more error checking.


>
> The implemation file is as follows:
>
> //************************************************** ************************
> *******
> //*** This is theimplementation file of DayTime class
> //************************************************** ************************
> *******
>
> #include "daytime.h"
> #include <iostream>
>
> using namespace std;
>
> // private members of class
>
> // enum days {ERROR, Sun, Mon, Tues, Wen, Thu, Fri, Sat} day;
>
> // int hour;
>
> // int min;
>
> //Class declrations
>
> //************************************************** ************************
> *******
>
> DayTime::DayTime() // default constructor
>
> // Precondition:
> // None
>
> //Postsondition:
> // Constructed, day set to ERROR, how and min set to "0"
>
> {
>
> day = ERROR;
>
> hour = 0;
>
> min = 0;
>
> }

Prefer an initialization list:
DayTime::DayTime()
: day(ERROR), hour(0), min(0)
>
> //************************************************** ************************
> *******
>
> void DayTime::operator>> (/* in */ ifstream& anyFile)
>
> // Precondition:
> // stream is in day/hour/min order
> //0 < Day < 8 , -1 < Hour < 24 , and -1 < Min < 60
>
> //Postcondition:
>
> // Day, hour, and minute are set
>
> {
> int inDay;
>
> int inHour;
>
> int inMin;
>
> anyFile >> inDay >> inHour >> inMin;
>
> //debug statement
> cout << inDay << inHour << inMin;

cout << "Day: " << inDay
<< ", Hour: " << inHour
<< ", Min: " << inMin
<< endl;


>
> switch (inDay) // use inDay to set enum day
> {
> case 1 : day = Sun;
>
> break;

[snip -- many cases]
The compiler can convert an enum value into an integer and
an integer into an enum value, provided that the integer
is within the range of an enum.
day = inDay;

Check out this article:
http://www.embedded.com/story/OEG20030319S0021

> default: cout << "Error!" << endl;
>
> break;
> }
>
> hour = inHour;
>
> min = inMin;
> }


This could be simplified:
anyFile >> (int) day >> hour >> min;

>
> //************************************************** ************************
> *******
>
> void DayTime::operator<<(DayTime otherDayTime)
>
> //Precondition:
> // DayTime has been set
>
> //Postcondition:
> // private members are displayed to the screen in
>
> // DDD HH:MM 'endl'
> //format
>
> {
> cout << day << " ";
>
> if (hour < 10)
>
> cout << "0";
>
> cout << hour << ":";
>
> if (min < 10)
>
> cout << "0";
>
> cout << min << endl;
>
> }

This could be simplified by using the width() and fill() functions:
int saved_width;
char saved_fill;

saved_width = cout.width(2);
saved_fill = cout.fill('0');
cout << hour << ":" << min << endl;
cout.width(saved_width);
cout.fill(saved_fill);


[snip -- definition of operator==()]

> //************************************************** ************************
> *******
>
> bool DayTime::operator <(/* in */ DayTime otherDayTime)
>
> //Precondition:
> // Current and otherDayTime are declared
>
> //Postcondition:
> // if DayTime < otherDayTime, returns true
> // else, returns false
>
> {
> if (day < otherDayTime.day)
> return true;
>
> if (day == otherDayTime.day &&
> hour < otherDayTime.hour)
>
> return true;
>
> if (day == otherDayTime.day &&
> hour == otherDayTime.hour &&
> min <otherDayTime.min)
>
> return true;
>
> return false;
> }

Try something like this:
{
if (day != otherDayTime.day)
return day < otherDayTime.day;

if (hour != otherDayTime.hour)
return hour < otherDayTime.hour;

return min < otherDayTime.min;
}

In essence, the hours only need to be compared if the day values
are equal. Minutes only need to be compared if the hours are
equal.


[Example output snipped]

> Any help is greately appericated.
>
> Revman



--
Thomas Matthews

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