Assignment operator

[Claire]

Hey guys!
I posted a msg b4 about having to include an assignment operator in my code for a program that outputs a calender. My tutor has already declared it for a hint for us as:

Calender& operator= (const Calender& rhs);

The thing is, we don't actually need to incorporate it into our code. Our tutor just wants us to define it, but I'm unsure of how to do that.
mOST of my code is as follows (by the way, I know some of it is not right!!

//assign2.cpp


#include <iostream>
#include <string>
#include <iomanip>
#include <cmath>

class Calender

{
public:
Calender(); //constructor requests user to input a 4 digit year

Calender& operator= (const Calender& rhs); //Assignment operator

void CreateCalender(); //Fills 'theCalender' array with all the dates of the year

void Display(); //Displays the calender to the screen

int FirstDayOfMonth(int mm); //Calulates which day
// of the week the first day of month occurs and returns an int // between 0-6

bool IsLeapYear(); //Returns true if the year is a leap yr, or else returns false


private:
int year; //Holds the 4 digit year

int theCalender[12][35]; //holds all the dates for the year

};


//************************************************** *************************************8
//constructor
//************************************************** **************************************
Calender::Calender()
{
cout << " Please enter a year" << endl;
cin >> year;

if (year < 1582 || year > 4902)
cout << "Year is before or after Gregorian caldender was accepted. Please enter a year between 1582 and 4902" << endl;

}


//Assignment operator
Calender& operator= (const Calender& rhs);
{
WHAT DO I WRITE HERE?!
}



//************************************************** **********************************8
//Fills 'theCalender' array with all the dates of the year
//************************************************** **********************************
void Calender::CreateCalender()
{
int i, j, mm, date, temp, loopCount;
mm = 1;
date = 1;


//initialising the days
int theCalender[12][35];
for (int i=0; i<12; i++)
{
for (int j=0; j<35; j++)
theCalender[i][j] = 0;
}

while (mm <= 12)
{
date = 1;


if (mm ==1) //if jan
for (int j =0; j <31; j++)
{
theCalender[0][j] = date;
date++;
}
date = 1;


if (mm == 2) //if feb
{
if (IsLeapYear())
for (j =0; j <29; j++)
{
theCalender[1][j]=date;
date++;
}
else
for (j =0; j <28; j++)
{
theCalender[1][j]=date;
date++;
}
}
date=1;


if (mm ==3) //if march
for (j =0; j <31; j++)
{
theCalender[2][j]=date;
date++;
}
date = 1;


if (mm ==4) //if april
for (j =0; j <30; j++)
{
theCalender[3][j]=date;
date++;
}
date = 1;

if (mm ==5) //if may
for (j =0; j <31; j++)
{
theCalender[4][j] =date;
date++;
}
date = 1;


if (mm ==6) //if june
for ( j =0; j <30; j++)
{
theCalender[5][j] = date;
date++;
}
date=1;


if (mm ==7) //if july
for ( j =0; j <31; j++)
{
theCalender[6][j]=date;
date++;
}
date=1;

if (mm ==8) //if august
for ( j =0; j <31; j++)
{
theCalender[7][j]=date;
date++;
}
date=1;

if (mm ==9) //if sep
for ( j =0; j <30; j++)
{
theCalender[8][j]=date;
date++;
}
date=1;

if (mm ==10) //if oct
for (j =0; j <31; j++)
{
theCalender[9][j]=date;
date++;
}
date=1;

if (mm ==11) //if nov
for ( j =0; j <30; j++)
{
theCalender[10][j]=date;
date++;
}
date=1;

if (mm ==12) //if dec
for (j =0; j <31; j++)
{
theCalender[11][j]=date;
date++;
}
date=1;



//counts the loops and shifts the no's down
loopCount = 0;
while (loopCount < FirstDayofMonth(mm)) {
temp = theCalender[i][34]; / /put the last value of the array into a temp position
for (j=34; j>0; j--) //must count backwards
{
theCalender[i][j] = theCalender[i][j-1]; //moves the value into the position next to it on it's right
}
theCalender[i][0] = temp;
loopCount ++;
}



mm ++;
} // end while loop




} //end createCalender() loop



//************************************************** **********************
//Displays the calender to the screen
//************************************************** **********************
void Calender:isplay()
{
int i, j, mm;

for (i=0; i<12; i++)
{
cout <<endl;
for (j=0, j<35; j++)
cout theCalender[i][j];
}

}


//************************************************** ****************************************8
//Calulates which day of the week the first day of month occurs and returns an int between 0-6
//************************************************** ***************************************8

int Calender::FirstDayOfMonth(int mm)
{
int yyyy = year;
int mm = month;
int adjustedMonth;
int yearPart, centuryPart, sum, result;

if (mm<3)
adjustedMonth = mm+10;

if (mm >=3)
adjustedMonth = mm-2;

yyyy = year;

if (adjustedMonth == 11)
yyyy = year-1;

if (adjustedMonth == 12)
yyyy = year-1;

yearPart = (yyyy%100);

centuryPart = (yyyy/100);

sum = (dd + floor(2.6 * adjustedMonth - 0.2) + yearPart + floor(yearPart / 4) + floor(centuryPart / 4) - 2 * centuryPart);

result = (sum % 7);

if (result <0)
result = result + 7;

return result;

}


//************************************************** ***************************************
//Returns true if the year is a leap yr, or else returns false
//************************************************** ****************************************
bool IsLeapYear()
{
int leap;

if (yearPart = 0)
if { yyyy%400 = 0) return true;

else
leap = yyyy%4; if (leap = 0)
return true; else return false;

return;
}

[Unregistered]

You dont actually need it here because you don't hold any pointers inside your class, a binary copy will do just fine, but you could just copy the data from the object being passed by reference to your operator. And it is defined like this:

class Calender {
...
    // Inside the class
    Calender& operator = (const Calender& rhs);
...
private:
    int year;
    int theCalender[12][35];
};
...
//Outside the class you need the "ClassName::" like any member function
Calender& Calender :: operator = (const Calender& rhs) 
{
    // Here all you have to do is copy the fields from rhs

    return *this; // Returns a reference to this object
}

Hope this helps.

[Claire]

How would that assignment operator go?

Would I have to do, say, make anything equal to .rhs??
I'm unsure of what the total code would be. How would I copy it?


Thanks@!

[Unregistered]

Calender& Calender :: operator = (const Calender& rhs) 
{
    // You just copy field by field
    year = rhs.year;

    // For the array use memcpy
    memcpy( theCalender, rhs.theCalender, sizeof(theCalender) );

    return *this; // Returns a reference to this object
}

And now you can use it like this:

#include ....
...
int main() {
    Calender c1, c2;
    // Do some stuff
    ...
    // Use it like this
    c2 = c1; // This just copies c1.year and c1.theCalender into c2.year and c2.theCalender
}