Question about the this pointer

[Schizoid Man]

Hello,

Suppose I have a class called ModDate that contains three private
members - day, month, year - all defined as int.

I want to overload the += operator and add an integer value to the date
to get the new date after increments.

To do that I have the following method:

const ModDate &ModDate:perator+=(int addDays) {
for (int i = 0; i < addDays; i++)
incrementDay();
return *this;
}

However, when I call this method in the following lines, I get compile
error C2676 binary '<<' : no operator found which takes a right-hand
operand of type 'const ModDate' (or there is no acceptable conversion)
with Visual C++.

ModDate enDate1;
enDate1.setDate(1, 1, 2001);
cout << "After increment: " << (enDate1 += 7);

I would appreciate any advice.

Thanks.

 

[benben]

Hello,

Suppose I have a class called ModDate that contains three private
members - day, month, year - all defined as int.

I want to overload the += operator and add an integer value to the date
to get the new date after increments.

To do that I have the following method:

const ModDate &ModDate:perator+=(int addDays) {
for (int i = 0; i < addDays; i++)
incrementDay();
return *this;
}

However, when I call this method in the following lines, I get compile
error C2676 binary '<<' : no operator found which takes a right-hand
operand of type 'const ModDate' (or there is no acceptable conversion)
with Visual C++.

ModDate enDate1;
enDate1.setDate(1, 1, 2001);
cout << "After increment: " << (enDate1 += 7);

If you haven't defined operator<< how the hell the compiler's gonna know
how to output your date?

I would appreciate any advice.

Thanks.

Ben

 

[Ian Collins]

Hello,

Suppose I have a class called ModDate that contains three private
members - day, month, year - all defined as int.

I want to overload the += operator and add an integer value to the date
to get the new date after increments.

To do that I have the following method:

const ModDate &ModDate:perator+=(int addDays) {
for (int i = 0; i < addDays; i++)
incrementDay();
return *this;
}

However, when I call this method in the following lines, I get compile
error C2676 binary '<<' : no operator found which takes a right-hand
operand of type 'const ModDate' (or there is no acceptable conversion)
with Visual C++.

ModDate enDate1;
enDate1.setDate(1, 1, 2001);
cout << "After increment: " << (enDate1 += 7);

Nothing to do with the this pointer, looks like you haven't defined a <<
operator for ModDate.

 

[Schizoid Man]

Nothing to do with the this pointer, looks like you haven't defined a <<
operator for ModDate.

Hi Ian,

I now understand the necessity to post complete code. My code the
overloading of the << operator is included below.

I did make a modification to the original overloading declaration. Now,
using it as

const ModDate &ModDate:perator+(int addDays)

and calling it in the following manner

enDate1.setDate(1, 1, 2001);
enDate1 = enDate1 + 7;
cout << enDate1;

seems to work just fine. Once I got rid of the = sign, it worked as I
expected. Unfortunately with the = sign back, I still get the same
compile error.

Thanks,
Schiz

ostream &operator<< (ostream &strm, ModDate &date) {
switch(date.month) {
case 1:
strm << "January";
break;
case 2:
strm << "February";
break;
case 3:
strm << "March";
break;
case 4:
strm << "April";
break;
case 5:
strm << "May";
break;
case 6:
strm << "June";
break;
case 7:
strm << "July";
break;
case 8:
strm << "August";
break;
case 9:
strm << "September";
break;
case 10:
strm << "October";
break;
case 11:
strm << "November";
break;
case 12:
strm << "December";
break;
default:
strm << " ";
break;
}

 

[Kai-Uwe Bux]

Hi Ian,

I now understand the necessity to post complete code. My code the
overloading of the << operator is included below.

I did make a modification to the original overloading declaration. Now,
using it as

const ModDate &ModDate:perator+(int addDays)

and calling it in the following manner

enDate1.setDate(1, 1, 2001);
enDate1 = enDate1 + 7;
cout << enDate1;

seems to work just fine. Once I got rid of the = sign, it worked as I
expected. Unfortunately with the = sign back, I still get the same
compile error.

Thanks,
Schiz

ostream &operator<< (ostream &strm, ModDate &date) {
switch(date.month) {
case 1:
strm << "January";
break;
case 2:
strm << "February";
break;
case 3:
strm << "March";
break;
case 4:
strm << "April";
break;
case 5:
strm << "May";
break;
case 6:
strm << "June";
break;
case 7:
strm << "July";
break;
case 8:
strm << "August";
break;
case 9:
strm << "September";
break;
case 10:
strm << "October";
break;
case 11:
strm << "November";
break;
case 12:
strm << "December";
break;
default:
strm << " ";
break;
}

The operator<< does not take a const reference. Therefore, the return type
of operator+= does not match.


Best

Kai-Uwe Bux

 

[Kai-Uwe Bux]

Hello,

Suppose I have a class called ModDate that contains three private
members - day, month, year - all defined as int.

I want to overload the += operator and add an integer value to the date
to get the new date after increments.

To do that I have the following method:

const ModDate &ModDate:perator+=(int addDays) {
for (int i = 0; i < addDays; i++)
incrementDay();
return *this;
}

This is probably unrelated to your problem, however: are you sure about the
int parameter? It suggests that negative values are permissible inputs. For
those, the natural interpretation would be that the date is decremented,
but the code will not do that.

However, when I call this method in the following lines, I get compile
error C2676 binary '<<' : no operator found which takes a right-hand
operand of type 'const ModDate' (or there is no acceptable conversion)
with Visual C++.

ModDate enDate1;
enDate1.setDate(1, 1, 2001);
cout << "After increment: " << (enDate1 += 7);

Best

Kai-Uwe Bux