[VC++] Operator overloading: error C2679 / C2678


C

c++newbie

Hi all,

I try to compile the following classes:

main.cpp:

#include <algorithm>
#include <iostream>
#include <fstream>
#include <iterator>
#include <vector>
#include <functional>
#include "student.h"

using namespace std;

int main(int argc, char **argv) {
if (argc < 3 || argc > 3) {
cerr << "Usage: " << argv[0] << " <infile> <outfile>" << endl; exit(1);
}
ifstream input(argv[1]);
ofstream output(argv[2]);
istream_iterator<Student> inputIterator(input);
ostream_iterator<Student> outputIterator(output);
vector<Student> Students;

copy(inputIterator, istream_iterator<Student>(),
back_inserter(Students));

sort(Students.begin(), Students.end());
vector<Student>::iterator new_end = unique(Students.begin(),
Students.end());
stable_sort(Students.begin(), new_end, cmpGrade);
for_each(Students.begin(), new_end, mem_fun_ref(&Student::toCout));

output << "<?xml version=\"1.0\"?>" << endl << "<Students>" << endl;
copy(Students.begin(), new_end, outputIterator);
output << "</Students>" << endl;

return 0;
}

student.h:

#include <algorithm>
#include <iostream>
#include <fstream>
#include <iterator>
#include <vector>
#include <functional>

using namespace std;

class Student {

private:
string name, first, place, gender, grade;

public:
Student() { }
~Student() { }
string getName() const { return name; }
string getFirst() const { return first; }
string getPlace() const { return place; }
string getGender() const { return gender; }
string getGrade() const { return grade; }
void toCout() { cout << *this; }

friend ostream& operator <<(ostream &os, const Student &s) {
os << "Student name=\"" << s.getName() << "\" "
<< "first=\"" << s.getFirst() << "\" "
<< "place=\"" << s.getPlace() << "\" "
<< "gender=\"" << s.getGender() << "\" "
<< "grade=\"" << s.getGrade() << "\" />"
<< endl;
return os;
};

friend istream& operator >>(istream &is, Student &s) {
string line;
char buf[128];
is.getline(buf, sizeof(buf), ','); s.name.assign(buf);
is.getline(buf, sizeof(buf), ','); s.first.assign(buf);
is.getline(buf, sizeof(buf), ','); s.place.assign(buf);
is.getline(buf, sizeof(buf), ','); s.gender.assign(buf);
is.getline(buf, sizeof(buf), '\n'); s.grade.assign(buf);
return is;
};

friend bool operator<(const Student &s1, const Student &s2) {
return lexicographical_compare(
s1.getName().begin(), s1.getName().end(),
s2.getName().begin(), s2.getName().end());
};

friend bool cmpGrade(const Student &s1, const Student &s2) {
return lexicographical_compare(
s1.getGrade().begin(), s1.getGrade().end(),
s2.getGrade().begin(), s2.getGrade().end());
};

friend bool operator==(const Student &s1, const Student &s2) {
return s1.getName() == s2.getName() &&
s1.getFirst() == s2.getFirst() &&
s1.getPlace() == s2.getPlace() &&
s1.getGender() == s2.getGender() &&
s1.getGrade() == s2.getGrade();
};
};

Compiling these classes gives the following output:

d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(31) :
error C2679: binary '<<' : no operator defined which takes a right-hand
operand of type 'class std::basic_string<char,struct
std::char_traits said:
' (or there is no acceptable conversion)
d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(64) :
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)
d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(65) :
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)
d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(66) :
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)
d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(67) :
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)
d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(68) :
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)

I already tried to explicitly import <string> in student.h, but then I
receive the following error:

d:\program files\microsoft visual studio\vc98\include\functional(263) :
error C2562: '()' : 'void' function returning a value
d:\program files\microsoft visual
studio\vc98\include\functional(262) : see declaration of '()'
d:\program files\microsoft visual
studio\vc98\include\functional(263) : while compiling class-template member
function 'void __thiscall std::mem_fun_ref_t<void,class Student>::eek:perator
()(class Student &) const'

Can anyone help please?

Regards,

Matthijs.
 
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S

Sharad Kala

c++newbie said:
Hi all,

I try to compile the following classes:

main.cpp:
[snip]
Can anyone help please?
I see that you have used std::string but there is no inclusion of <string>
i.e. add this line - #include <string>.

Sharad
 
C

c++newbie

Sharad Kala said:
c++newbie said:
Hi all,

I try to compile the following classes:

main.cpp:
[snip]
Can anyone help please?
I see that you have used std::string but there is no inclusion of <string>
i.e. add this line - #include <string>.

Sharad

I already tried to explicitly import <string> in student.h, but then I
receive the following error:

d:\program files\microsoft visual studio\vc98\include\functional(263) :
error C2562: '()' : 'void' function returning a value
d:\program files\microsoft visual
studio\vc98\include\functional(262) : see declaration of '()'
d:\program files\microsoft visual
studio\vc98\include\functional(263) : while compiling class-template member
function 'void __thiscall std::mem_fun_ref_t<void,class Student>::eek:perator
()(class Student &) const'

Matthijs.
 
C

c++newbie

Sharad Kala said:
Which VC ? It compiled for me on VC 8 after inclusion of the header.

Sharad

PS - I can't swear that there are no other problems in the code though.
VC++ 6.0.
 
M

msalters

c++newbie said:
Hi all,

I try to compile the following classes:

main.cpp: ....
Compiling these classes gives the following output:

d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(31)
:
error C2679: binary '<<' : no operator defined which takes a right-hand
operand of type 'class std::basic_string<char,struct

d:\develop\acpp\generiekealgortihmen\generieke_algortimen\student.h(64)
:
error C2678: binary '==' : no operator defined which takes a left-hand
operand of type 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >
' (or there is no acceptable conversion)

That means you forgot both <string> and <ostream>

BTW, I saw you're using VC6.0, and you're a Dutch student. You
should be able to get a cheap VC7 license from SurfSpot. It's
a lot better.

Regards,
Michiel Salters
 
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C

c++newbie

msalters said:
That means you forgot both <string> and <ostream>

BTW, I saw you're using VC6.0, and you're a Dutch student. You
should be able to get a cheap VC7 license from SurfSpot. It's
a lot better.

Regards,
Michiel Salters

Yeah should try at least 7.0 as I experienced problems with an earlier
assignment as well. Sharad Kala could compile the same code as is without
any problems using VC8. Hope that helps.

Greetz.
Matthijs.
 
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Joined
Feb 12, 2008
Messages
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I'm having a similar problem..Here is my coding as is.

/*
Program: King Hardware Store Inventory Program
Programmer: Travis Skillin
Date: 2/9/2008
Program: MidTermTS
Version: 1

This program will allow the user to enter an item number, on hand amount and on order amount, as well as price.
*/
/* ------preprocessing directives -----------------------------------------*/

#include <iostream>
#include <cstring>
#include <iomanip>
#include <string>

using namespace std;


/* ------function prototypes ----------------------------------------------*/

int KeyIt(char[25]);
void loop();

/* ----- Global Variables -------------------------------------------------*/
/* input variables */
int ItemNum = 0; /*Denotes the item number*/
int UnitCost = 0; /*The units cost*/
int OnHand; /*shows the amount on hand*/
float OrderCost = 0;
char answer ;
int needed; /*Amount that needs to be reordered.*/

string descrip[6] = {
"Hammer",
"Saw",
"Drill",
"Screwdriver",
"Pliers",
"INVALID",
};

float Data[6][7] =

{
{1000,1999,12,24,0,0,0},
{2000,2999,3,4,0,0,0},
{3000,3999,4,5,0,0,0},
{4000,4999,50,75,0,0,0},
{5000,5999,12,36,0,0,0},
{6000,9999,0,0,0,0,0}
};


/* -------------------------------------------------------------------------
Main Module
---------------------------------------------------------------------------*/

int main()
{int fIndex(int num);
int n;
int x;
do

{
cout <<
"****************************************************************************" << endl;
cout << " King Hardware Store Inventory Program " << endl;
cout <<
"****************************************************************************" << endl;
ItemNum = KeyIt("Item Number: ");
n = fIndex(ItemNum);
cout<< " "<<endl;
OnHand = KeyIt("Qty on Hand: ");
cout<< " "<<endl;
UnitCost = KeyIt("Unit Cost: $");
cout<< " "<<endl;
system("pause");
system("cls");
cout <<

Data[n][4] << OnHand;

Data[n][6] = 0;
if ( Data[n][4] <= Data[n][2]) {
Data[n][6] = Data[n][2] - Data[n][4];
if ( Data[n][6] == 0 ) Data[n][6]++;
}


cout<< "****************************************************************************" << endl;
cout << " King Hardware Store Individual Item Reorder information " << endl;
cout <<
"****************************************************************************" << endl;
cout << "Item"" ""Qty"" ""On"" ""Item"" "<<endl;
cout << "Number"" ""Description"" ""on Hand"" ""Order"" ""Cost"<<endl;
cout << descrip[x];
cout << ": Item #: ";
cout <<Data[n][1];
cout << "-";
cout << Data[n][2];
cout << " On Hand: ";
cout << Data[n][5];
cout << " Price: $";
cout << Data[n][6];
loop();
system("cls");
}while (answer == 'N' || answer== 'n');

}
/* -------------------------------------------------------------------------
Name: KeyIt
Desc: Get keyboard input
Return: float -- value entered
Parameters: char -- prompt
---------------------------------------------------------------------------*/
int KeyIt(char desc[25])
{
int fInputNum;
cout << desc;
cin >> fInputNum;
//get rid of the enter key
cin.ignore();

return fInputNum;
}
void loop()
{
cout << "Are we done for the day? Yes/No? ";
cin>> answer;
cin.ignore();
return;
}
int fIndex(int num){
int x;
for(x=0;x<5;x++){
if( Data[x][0] < num && num < Data[x][1] ) return x;
}
return x;
}


Ok, I edited my post because I fixed my problem. Now for the fun part. I need to pull information from my array and have it display on my screen.
 
Last edited:

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