C++ help - read/write to/from file

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#include "stdafx.h" //dont worry about this heading, its automatically generated

#include<iostream>

#include<cstdlib> //for system commands

using namespace std;



class dateType



{



public:



void setDate(int month, int day, int year);



//Function to set the date.



//The member variables dMonth, dDay, and dYear are set



//according to the parameters.



//Postcondition: dMonth = month; dDay = day; dYear = year





int getDay() const;



//Function to return the day.



//Postcondition: The value of dDay is returned.





int getMonth() const;



//Function to return the month.



//Postcondition: The value of dMonth is returned.





int getYear() const;



//Function to return the year.



//Postcondition: The value of dYear is returned.





void printDate() const;



//Function to output the date in the form mm-dd-yyyy.





dateType(int month = 1, int day = 1, int year = 2000);



//Constructor to set the date



//The member variables dMonth, dDay, and dYear are set



//according to the parameters.



//Postcondition: dMonth = month; dDay = day; dYear = year. If



// no values are specified, the default values are used to



// initialize the member variables.



bool isLeapYear(int);



friend ostream& operator<<(ostream& , const dateType&);

friend istream& operator>> ( istream& , dateType&);



dateType operator++(int);

dateType operator--(int);

bool operator <(const dateType& date);

bool operator >(const dateType& date);

bool operator ==(const dateType& date);

bool operator !=(const dateType& date);



private:



int dMonth; //variable to store the month



int dDay; //variable to store the day



int dYear; //variable to store the year



};







void dateType::setDate(int month, int day, int year)



{bool error=false;



int max=28;



switch(month)



{

    case 1 :case 3 :case 5 :case 7 :case 8 :

    case 10:case 12:

        if (day > 31)

            error=true;

        break;



case 4 :case 6 :case 9 :case 11:

    if (day > 30)

        error=true;

    break;



    case 2 :

        if(isLeapYear(year))

            max=29;

        if(day>max)

            error=true;

}



if(error)

{

    cout<<"invalid date "<<month<<"/"<<day<<"/"<<year<<" entered. Jan 1, 2000 being used\n";



month=1;



day=1;



year=2000;



}



dMonth = month;



dDay = day;



dYear = year;



}





bool dateType::isLeapYear(int year)

{

    if((year%4==0 && year%100!=0)||(year%400==0))

        return true;



    return false;



}



int dateType::getDay() const



{



return dDay;



}





int dateType::getMonth() const



{



return dMonth;



}





int dateType::getYear() const



{



return dYear;



}





void dateType::printDate() const



{



cout << dMonth << "-" << dDay << "-" << dYear;



}





//Constructor with parameters



dateType::dateType(int month, int day, int year)



{



setDate(month, day, year);



}



ostream& operator<<(ostream& os, const dateType& date)

{

    if(date.dMonth<10)

        os<<"0";



    os <<date.dMonth<<"-";



    if(date.dDay<10)

        os<<"0";

    os << date.dDay << "-"  ;

    if(date.dYear<1000)

        os<<"0";

    if(date.dYear<100)

        os<<"0";

    os<< date.dYear;

    return os;

}



istream& operator>> ( istream& is, dateType& date )

{

   is >> date.dMonth>> date.dDay >> date.dYear;

   return is;

}





dateType dateType::operator++(int){

    dateType date(dMonth,dDay,dYear);



        dDay++;//increment day first



        //take account for end of year

        if(dMonth==12 && dDay>31){

          dMonth=1;

          dDay=1;

          dYear+=1;

        }



    //take account new month

        if(dDay>31){

            dMonth++;

            dDay=1;

        }



        if(dDay==0){

            dMonth--;

            dDay=31;

        }



    // take account that certain days max out at 30 days

        if((dDay==31)&&((dMonth%12==4)||(dMonth%12==6)||(dMonth%12==9)||(dMonth%12==11))){

            dMonth++;

            dDay=1;

        }



    //normalize to 12 months

        if(dMonth>12){

            dMonth-=12;

            dYear++;

        }



    //take account of leap year

    if((dMonth==2 )&& (dDay>28)){

        if(!isLeapYear(dYear)){

            dMonth=3;

            dDay-=28;

        }

        else{

            if(dDay>29){

                dMonth=3;

                dDay-=29;

            }

        }

    }

    return date;

}



dateType dateType::operator--(int){

    dateType date(dMonth,dDay,dYear);



    //only thing to worry about is if 1st of month

    if(dDay!=1){

        dDay--;

        return date;

    }





    dMonth--;//go ahead and decement month



    //normalize to 12 months

        while(dMonth>12){

            dMonth-=12;

            dYear++;

        }

        while(dMonth<1){

            dMonth+=12;

            dYear--;

        }



    switch(dMonth){

        case 1:

            dDay=31;

            dYear--;

            break;



        case 2: //fe

            dDay=28;

            if(isLeapYear(dYear))

                dDay++;

            break;

        case 4: case 6: case 9: case 11://30 days only

            dDay=30;

            break;



        default:

            dDay=31;

    }



    return date;

}





bool dateType::operator <(const dateType& date){

    if(*this==date)

        return false;



    if(dYear>date.getYear())

        return false;

    if(dYear<date.getYear())

        return true;



    if(dMonth>date.getMonth())

        return false;

    if(dMonth<date.getMonth())

        return true;



    if(dDay>date.getDay())

        return false;



    return true;

}

bool dateType::operator >(const dateType& date){

    if (*this==date)

        return false;

    return !(*this<date);

}

bool dateType::operator ==(const dateType& date){

    return((dYear==date.getYear())&&(dMonth==date.getMonth())&&(dDay==date.getDay()));

}

bool dateType::operator !=(const dateType& date){

    return !(*this==date);

}









int main()

{

    dateType d1(2,29,2011);



    cout<<"First date is ";



    d1.printDate();



    cout<<endl;



    d1--;

    cout<<"Decrementing the date is now: "<<d1<<endl;



    dateType d2(2,29,2008);



    cout<<"Second date is ";



    d2.printDate();



    cout<<endl;



    d2++;

    cout<<"Incrementing the date is now: "<<d2<<endl;



    



    system("pause");



    return 0;



}


The code compiles just fine. and everything works perfectly but i want it to read/write to/from a file. I know i need to declare #include <fstream> in the heading. Can anyone help me with rest please.
You can do that the same way you do with the istream/ostream
you overload the << and >> for ifstream and ofstream

something like this:
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friend ofstream& operator<<(ofstream& , const dateType&);

friend ifstream& operator>> ( ifstream& , dateType&);

Should work, haven't tested.
Last edited on
cin and ifstream are input stream buffers. They are both istreams.

cout and ofstream are output stream buffers. They are both ostreams.

You could even do this:
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friend ostream& operator<<(ostream& out, const dataType& type)
{  return out << type.memberA << " " << type.memberB; }

//
dataType myType;
ofstream out("file.txt");
cout << myType;
out << myType;


You can default ostreams if they are appropriatly placed in the parameters:
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void print(int i, ostream& out = cout)
{
  if (out == cout) out << "You are printing to the console\n";
  out << i;
}





do

#include <fstream>

to read

ifstream File ("filename");

to write

ofstream File

File.open("filename", fstream::in | fstream::app);
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