unresolved external symbol

[pat270881]

hello,

I use the Visual C++ 2005 Express Edition and I want to implement a
simple c++ programm which has a header file and a implementation file.

the header file:

#include <iostream>
 
namespace main_savitch_2C
{
class statistician
{
public:
void next(double r);
 
private:
int count;
};
}
 

and the implementation file which contains now only the definitions:

#include "stats.h"
 
using namespace main_savitch_2C;
 
 
void statistician::next(double r)
{
 
}
 

But when I try to compile this very simple program, the following error
occurs:

------ Build started: Project: Test, Configuration: Debug Win32 ------
Compiling...
statsimpl.cpp
Linking...
msvcrtd.lib(crtexe.obj) : error LNK2019: unresolved external symbol
_main referenced in function ___tmainCRTStartup
C:\Dokumente und Einstellungen\Patrick\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Debug\Assignment4.exe : fatal error LNK1120:
1 unresolved externals
Build log was saved at "file://c:\Dokumente und
Einstellungen\matti\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Assignment4\Debug\BuildL og.htm"
Assignment4 - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==========

I look for the error for many hours but I simply do not find how I can
fix it :( Does anybody know here how I can fix this error?? :((

Regards

[Thomas J. Gritzan]

pat270881 schrieb:

hello,

I use the Visual C++ 2005 Express Edition and I want to implement a
simple c++ programm which has a header file and a implementation file.

[snip]

Here the linker clearly states what he is missing:

msvcrtd.lib(crtexe.obj) : error LNK2019: unresolved external symbol
_main referenced in function ___tmainCRTStartup

You need to define a main() function:

int main() // or:
int main(int argc, char* argv[])

--
Thomas
http://www.netmeister.org/news/learn2quote.html

[pat270881]

okay thank you very much! unfortunately I have one more problem, I have
now the following:

the header file:

#include <iostream>
 
namespace main_savitch_2C
{
class statistician
{
public:
void next(double r);
 
private:
 
 
bool operator ==(const statistician& s1, const statistician& s2)
{
return true;
}
 

and my testfile:
[code]
#include <iostream // Provides cout, cin
#include "stats.h"

using namespace main_savitch_2C;
using namespace std;

int main(int argc, char* argv[])
{
statistician s1, s2, s3;
if (s1 == s2)
cout << "s1 and s2 are equal." << endl;
else
cout << "s1 and s2 are not equal." << endl;
}

I know that the operator== function is not correctly implemented yet
but I want only test the overall running of the program, I implement
this function later. The objects s1, s2 and s3 are from statistician
and contain above other variables a number. But when I run this
programm I get the following error:

------ Build started: Project: Assignment4, Configuration: Debug Win32
------
Linking...
stattest.obj : error LNK2019: unresolved external symbol "bool __cdecl
main_savitch_2C::operator==(class main_savitch_2C::statistician const
&,class main_savitch_2C::statistician const &)"
(??8main_savitch_2C@@YA_NABVstatistician@0@0@Z) referenced in function
_main
C:\Dokumente und Einstellungen\Patrick\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Debug\Assignment4.exe : fatal error LNK1120:
1 unresolved externals
Build log was saved at "file://c:\Dokumente und
Einstellungen\Patrick\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Assignment4\Debug\BuildL og.htm"
Assignment4 - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==========

Do you know how I can fix this problem? Has this something to do with
the fact that the operator== is a non-member function??

Please help me once more.:(

Regards

[Thomas J. Gritzan]

pat270881 schrieb:

okay thank you very much! unfortunately I have one more problem, I have
now the following:

the header file:

#include <iostream>

namespace main_savitch_2C
{
    class statistician
    {
    public:
        void next(double r);

    private:


bool operator ==(const statistician& s1, const statistician& s2)
{
    return true;
}
 

This is obviously not your real code. There are some closing curly brackets
missing. Read this:
http://www.parashift.com/c++-faq-lit...t.html#faq-5.8

--
Thomas
http://www.netmeister.org/news/learn2quote.html

[pat270881]

What do you mean with that?? - This code is my real code, I try to get
it work, okay here once more my code:

The HEADER-File - stats.h:

#ifndef STATS_H // Prevent duplicate definition
#define STATS_H
#include <iostream>

namespace main_savitch_2C
{
class statistician
{
public:
// CONSTRUCTOR
statistician( );
// MODIFICATION MEMBER FUNCTIONS
void next(double r);
void reset( );
// CONSTANT MEMBER FUNCTIONS
int length( ) const;
double sum( ) const;
double mean( ) const;
double minimum( ) const;
double maximum( ) const;
// FRIEND FUNCTIONS
friend statistician operator +
(const statistician & s1, const statistician & s2);

private:
int count; // How many numbers in the sequence
double total; // The sum of all the numbers in the sequence
double tinyest; // The smallest number in the sequence
double largest; // The largest number in the sequence
};

// NON-MEMBER functions for the statistician class
bool operator ==(const statistician& s1, const statistician& s2);
}

#endif

The implementation-file - statsimpl.cpp:

#include "stats.h"
#include <iostream>
using namespace main_savitch_2C;
statistician::statistician()
{
count = 0;
total = 0;
tinyest = 0;
largest = 0;
}

void statistician::next(double r)
{
total += r;
std::cout << total << std::endl;
}

int statistician::length() const
{
return 0;
}

void statistician::reset( )
{
count = 0;
total = 0;
tinyest = 0;
largest = 0;
}

double statistician::sum() const
{
return total;
}

double statistician::mean() const
{
return total/count;
}

double statistician::minimum() const
{
return tinyest;
}

double statistician::maximum() const
{
return largest;
}

bool operator ==(const statistician& s1, const statistician& s2)
{
return true;
}

statistician operator + (const statistician & s1, const statistician &
s2)
{
statistician s3;

s3.next(s1.sum() + s2.sum());

return s3;
}

And when I try to test this with this testfile - statstest.cpp:

#include <cctype // Provides toupper
#include <iomanip // Provides setw to set the width of an output
#include <iostream // Provides cout, cin
#include <cstdlib // Provides EXIT_SUCCESS
#include "stats.h"

using namespace main_savitch_2C;
using namespace std;

void print_menu( )
{
cout << endl;
cout << "The following choices are available: " << endl;
cout << " R Activate one of the reset( ) functions" << endl;
cout << " 1 Add a new number to the 1st statistician s1" << endl;
cout << " 2 Add a new number to the 2nd statistician s2" << endl;
cout << " 3 Add a new number to the 3rd statistician s3" << endl;
cout << " T Print a table of values from the statisticians" <<
endl;
cout << " E Test whether s1 == s2" << endl;
cout << " + Set the third statistician s3 equal to s1 + s2" <<
endl;
cout << " * Set the third statistician s3 equal to x*s1" << endl;
cout << " Q Quit this test program" << endl;
}

char get_user_command( )
// Library facilties used: iostream.h
{
char command;

cout << "Enter choice: ";
cin >command;

return command;
}

double get_number( )
// Library facilties used: iostream.h
{
double result;

cout << "Please enter the next real number for the sequence: ";
cin >result;
cout << result << " has been read." << endl;
return result;
}

void print_values(const statistician& s)
// Library facilties used: iostream.h
{
cout << setw(10) << s.length( );
cout << setw(10) << s.sum( );
if (s.length( ) != 0)
{
cout << setw(10) << s.minimum( );
cout << setw(10) << s.mean( );
cout << setw(10) << s.maximum( );
}
else
cout << " none none none";
cout << endl;
}

int main(int argc, char* argv[])
{
statistician s1, s2, s3; // Three statisticians for us to play with
char choice; // A command character entered by the
user
double x; // Value for multiplication x*s1

cout << "Three statisticians s1, s2, and s3 are ready to test." <<
endl;

do
{
cout << endl;
print_menu( );
choice = toupper(get_user_command( ));
switch (choice)
{
case 'R': cout << "Which one should I reset (1, 2, 3) " << endl;
choice = get_user_command( );
switch (choice)
{
case '1': s1.reset( );
break;
case '2': s2.reset( );
break;
case '3': s3.reset( );
break;
}
cout << "Reset activated for s" << choice << "."
<< endl;
break;
case '1': s1.next(get_number( ));
break;
case '2': s2.next(get_number( ));
break;
case '3': s3.next(get_number( ));
break;

case '4': x = s1.sum();
cout << "Die Summe der Zahlen beträgt: " << x << endl;

x = s2.sum();
cout << "Die Summe der Zahlen beträgt: " << x << endl;
break;

case '+': s3 = s1 + s2;
cout << "s3 has been set to s1 + s2" << endl;
break;

case 'T': cout << "The values are given in this table:" <<
endl;
cout << " LENGTH SUM"
<< " MINIMUM MEAN MAXIMUM" << endl;
cout << " s1";
print_values(s1);
cout << " s2";
print_values(s2);
cout << " s3";
print_values(s3);
break;

case 'Q': cout << "Ridicule is the best test of truth." <<
endl;
break;
default: cout << choice << " is invalid. Sorry." << endl;
}
}
while ((choice != 'Q'));

return EXIT_SUCCESS;

}

I get the following error:

------ Build started: Project: Assignment4, Configuration: Debug Win32
------
Compiling...
statsimpl.cpp
Linking...
stattest.obj : error LNK2019: unresolved external symbol "class
main_savitch_2C::statistician __cdecl main_savitch_2C::operator+(class
main_savitch_2C::statistician const &,class
main_savitch_2C::statistician const &)"
(??Hmain_savitch_2C@@YA?AVstatistician@0@ABV10@0@Z ) referenced in
function _main
C:\Dokumente und Einstellungen\matti\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Debug\Assignment4.exe : fatal error LNK1120:
1 unresolved externals
Build log was saved at "file://c:\Dokumente und
Einstellungen\matti\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Assignment4\Debug\BuildL og.htm"
Assignment4 - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==========

This is the whole code, please help me with that, I simply can't find
the error...:((

Regards

matti

[Amit]

Hello Matti,

I don't have VC++ 2005 edition, so I tested your code on VC++ 2003
edition.

I made the following changes to get it working. Try making the same
changes at your end.

//Replace this function defination by the following defination
statistician operator + (const statistician & s1, const statistician &
s2)
{
statistician s3;

s3.next(s1.sum() + s2.sum());

return s3;

}

statistician main_savitch_2C::operator + (const statistician & s1,
const statistician &
s2)
{
statistician s3;

s3.next(s1.sum() + s2.sum());

return s3;

}

I hope this helps

Best Regards
-Amit Gupta

pat270881 wrote:

What do you mean with that?? - This code is my real code, I try to get
it work, okay here once more my code:

The HEADER-File - stats.h:

#ifndef STATS_H // Prevent duplicate definition
#define STATS_H
#include <iostream>

namespace main_savitch_2C
{
class statistician
{
public:
// CONSTRUCTOR
statistician( );
// MODIFICATION MEMBER FUNCTIONS
void next(double r);
void reset( );
// CONSTANT MEMBER FUNCTIONS
int length( ) const;
double sum( ) const;
double mean( ) const;
double minimum( ) const;
double maximum( ) const;
// FRIEND FUNCTIONS
friend statistician operator +
(const statistician & s1, const statistician & s2);

private:
int count; // How many numbers in the sequence
double total; // The sum of all the numbers in the sequence
double tinyest; // The smallest number in the sequence
double largest; // The largest number in the sequence
};

// NON-MEMBER functions for the statistician class
bool operator ==(const statistician& s1, const statistician& s2);
}

#endif

The implementation-file - statsimpl.cpp:

#include "stats.h"
#include <iostream>
using namespace main_savitch_2C;
statistician::statistician()
{
count = 0;
total = 0;
tinyest = 0;
largest = 0;
}

void statistician::next(double r)
{
total += r;
std::cout << total << std::endl;
}

int statistician::length() const
{
return 0;
}

void statistician::reset( )
{
count = 0;
total = 0;
tinyest = 0;
largest = 0;
}

double statistician::sum() const
{
return total;
}

double statistician::mean() const
{
return total/count;
}

double statistician::minimum() const
{
return tinyest;
}

double statistician::maximum() const
{
return largest;
}

bool operator ==(const statistician& s1, const statistician& s2)
{
return true;
}

statistician operator + (const statistician & s1, const statistician &
s2)
{
statistician s3;

s3.next(s1.sum() + s2.sum());

return s3;
}

And when I try to test this with this testfile - statstest.cpp:

#include <cctype // Provides toupper
#include <iomanip // Provides setw to set the width of an output
#include <iostream // Provides cout, cin
#include <cstdlib // Provides EXIT_SUCCESS
#include "stats.h"

using namespace main_savitch_2C;
using namespace std;

void print_menu( )
{
cout << endl;
cout << "The following choices are available: " << endl;
cout << " R Activate one of the reset( ) functions" << endl;
cout << " 1 Add a new number to the 1st statistician s1" << endl;
cout << " 2 Add a new number to the 2nd statistician s2" << endl;
cout << " 3 Add a new number to the 3rd statistician s3" << endl;
cout << " T Print a table of values from the statisticians" <<
endl;
cout << " E Test whether s1 == s2" << endl;
cout << " + Set the third statistician s3 equal to s1 + s2" <<
endl;
cout << " * Set the third statistician s3 equal to x*s1" << endl;
cout << " Q Quit this test program" << endl;
}

char get_user_command( )
// Library facilties used: iostream.h
{
char command;

cout << "Enter choice: ";
cin >command;

return command;
}

double get_number( )
// Library facilties used: iostream.h
{
double result;

cout << "Please enter the next real number for the sequence: ";
cin >result;
cout << result << " has been read." << endl;
return result;
}

void print_values(const statistician& s)
// Library facilties used: iostream.h
{
cout << setw(10) << s.length( );
cout << setw(10) << s.sum( );
if (s.length( ) != 0)
{
cout << setw(10) << s.minimum( );
cout << setw(10) << s.mean( );
cout << setw(10) << s.maximum( );
}
else
cout << " none none none";
cout << endl;
}

int main(int argc, char* argv[])
{
statistician s1, s2, s3; // Three statisticians for us to play with
char choice; // A command character entered by the
user
double x; // Value for multiplication x*s1

cout << "Three statisticians s1, s2, and s3 are ready to test." <<
endl;

do
{
cout << endl;
print_menu( );
choice = toupper(get_user_command( ));
switch (choice)
{
case 'R': cout << "Which one should I reset (1, 2, 3) " << endl;
choice = get_user_command( );
switch (choice)
{
case '1': s1.reset( );
break;
case '2': s2.reset( );
break;
case '3': s3.reset( );
break;
}
cout << "Reset activated for s" << choice << "."
<< endl;
break;
case '1': s1.next(get_number( ));
break;
case '2': s2.next(get_number( ));
break;
case '3': s3.next(get_number( ));
break;

case '4': x = s1.sum();
cout << "Die Summe der Zahlen beträgt: " << x << endl;

x = s2.sum();
cout << "Die Summe der Zahlen beträgt: " << x << endl;
break;

case '+': s3 = s1 + s2;
cout << "s3 has been set to s1 + s2" << endl;
break;

case 'T': cout << "The values are given in this table:" <<
endl;
cout << " LENGTH SUM"
<< " MINIMUM MEAN MAXIMUM" << endl;
cout << " s1";
print_values(s1);
cout << " s2";
print_values(s2);
cout << " s3";
print_values(s3);
break;

case 'Q': cout << "Ridicule is the best test of truth." <<
endl;
break;
default: cout << choice << " is invalid. Sorry." << endl;
}
}
while ((choice != 'Q'));

return EXIT_SUCCESS;

}

I get the following error:

------ Build started: Project: Assignment4, Configuration: Debug Win32
------
Compiling...
statsimpl.cpp
Linking...
stattest.obj : error LNK2019: unresolved external symbol "class
main_savitch_2C::statistician __cdecl main_savitch_2C::operator+(class
main_savitch_2C::statistician const &,class
main_savitch_2C::statistician const &)"
(??Hmain_savitch_2C@@YA?AVstatistician@0@ABV10@0@Z ) referenced in
function _main
C:\Dokumente und Einstellungen\matti\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Debug\Assignment4.exe : fatal error LNK1120:
1 unresolved externals
Build log was saved at "file://c:\Dokumente und
Einstellungen\matti\Eigene Dateien\Visual Studio
2005\Projects\Assignment4\Assignment4\Debug\BuildL og.htm"
Assignment4 - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped
==========

This is the whole code, please help me with that, I simply can't find
the error...:((

Regards

matti