Changing to multi-threaded debug

Hi everyone,

I have written a program which works OK when I build and run it as a multi-threaded debug DLL, but when I try and change the option in the 'code generation' menu to multi-threaded debug, I get some error messages and the project will not build. Here is my code - what am I doing wrong?

Code:

#include <iostream>
#include <cmath>
#include <conio.h>

using namespace std;

int main (){

float a;
float b;
float c;
float xone;
float xtwo;
int roots;
float discriminant;
float topline1;
float topline2;
float bottomline;
char name[50];
char ch;

cout << "\nWelcome to the quadratic equation solver. Please enter your name:" << endl;
cin.getline(name, 50);
start:
system("cls");
cout << "\nHello " << name << ". Please enter the X-squared coefficient (a):" << endl;
cin >> a;
system("cls");
cout << "\nEnter the X coefficient (b):" << endl;
cin >> b;
system("cls");
cout << "\nEnter the final constant (c):" << endl;
cin >> c;
system("cls");

discriminant = (pow(b, 2))-(4*a*c);
topline1 = (b*-1) + (sqrt(discriminant));
topline2 = (b*-1) - (sqrt(discriminant));
bottomline = (2*a);
xone = (topline1/bottomline);
xtwo = (topline2/bottomline);

if (discriminant < 0)
roots = 0;

else if (discriminant > 0)
roots = 2;

else if (discriminant == 0)
roots = 1;
 
cout << "\nYour two X values are  " << xone << "  and  " << xtwo << "  ." << endl;
cout << "\nYour discriminant is  " << discriminant << "  meaning that your number of roots is  " << roots << "  ." << endl;
cout << "\nPress enter to return to the start, or any other key to close.\n" << endl;

ch = _getch();
if (ch == 13)
goto start;

return 0;
}

You're not posting your error messages.

Sorry - I thought there may have been a straight-forward explanation because it works fine as a DLL, and I have never experienced this before...

Anyway, this is what I get in the output form of VC++ 2008 when I try to build the previously errorless code as a multi-threaded debug:

Code:

------ Build started: Project: Quadratic solver, Configuration: Debug Win32 ------
Compiling...
main.cpp
Linking...
main.obj : error LNK2005: "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl std::endl(class std::basic_ostream<char,struct std::char_traits<char> > &)" (?endl@std@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@1@AAV21@@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > & __thiscall std::basic_ostream<char,struct std::char_traits<char> >::operator<<(class std::basic_ostream<char,struct std::char_traits<char> > & (__cdecl*)(class std::basic_ostream<char,struct std::char_traits<char> > &))" (??6?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV01@P6AAAV01@AAV01@@Z@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > & __thiscall std::basic_ostream<char,struct std::char_traits<char> >::operator<<(int)" (??6?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV01@H@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: int __thiscall std::ios_base::flags(void)const " (?flags@ios_base@std@@QBEHXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > & __thiscall std::basic_ostream<char,struct std::char_traits<char> >::operator<<(float)" (??6?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV01@M@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: static bool __cdecl std::char_traits<char>::eq_int_type(int const &,int const &)" (?eq_int_type@?$char_traits@D@std@@SA_NABH0@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: static int __cdecl std::char_traits<char>::eof(void)" (?eof@?$char_traits@D@std@@SAHXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > & __thiscall std::basic_ostream<char,struct std::char_traits<char> >::flush(void)" (?flush@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEAAV12@XZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: void __thiscall std::basic_ios<char,struct std::char_traits<char> >::setstate(int,bool)" (?setstate@?$basic_ios@DU?$char_traits@D@std@@@std@@QAEXH_N@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_streambuf<char,struct std::char_traits<char> > * __thiscall std::basic_ios<char,struct std::char_traits<char> >::rdbuf(void)const " (?rdbuf@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEPAV?$basic_streambuf@DU?$char_traits@D@std@@@2@XZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_istream<char,struct std::char_traits<char> > & __thiscall std::basic_istream<char,struct std::char_traits<char> >::operator>>(float &)" (??5?$basic_istream@DU?$char_traits@D@std@@@std@@QAEAAV01@AAM@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_istream<char,struct std::char_traits<char> > & __thiscall std::basic_istream<char,struct std::char_traits<char> >::getline(char *,int)" (?getline@?$basic_istream@DU?$char_traits@D@std@@@std@@QAEAAV12@PADH@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: static unsigned int __cdecl std::char_traits<char>::length(char const *)" (?length@?$char_traits@D@std@@SAIPBD@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: char __thiscall std::basic_ios<char,struct std::char_traits<char> >::fill(void)const " (?fill@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEDXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: bool __thiscall std::ios_base::good(void)const " (?good@ios_base@std@@QBE_NXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: int __thiscall std::basic_streambuf<char,struct std::char_traits<char> >::sputc(char)" (?sputc@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEHD@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: void __thiscall std::basic_streambuf<char,struct std::char_traits<char> >::_Unlock(void)" (?_Unlock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: void __thiscall std::basic_ostream<char,struct std::char_traits<char> >::_Osfx(void)" (?_Osfx@?$basic_ostream@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: class std::basic_ostream<char,struct std::char_traits<char> > * __thiscall std::basic_ios<char,struct std::char_traits<char> >::tie(void)const " (?tie@?$basic_ios@DU?$char_traits@D@std@@@std@@QBEPAV?$basic_ostream@DU?$char_traits@D@std@@@2@XZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: void __thiscall std::basic_streambuf<char,struct std::char_traits<char> >::_Lock(void)" (?_Lock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEXXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: int __thiscall std::ios_base::width(void)const " (?width@ios_base@std@@QBEHXZ) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: int __thiscall std::ios_base::width(int)" (?width@ios_base@std@@QAEHH@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
main.obj : error LNK2005: "public: int __thiscall std::basic_streambuf<char,struct std::char_traits<char> >::sputn(char const *,int)" (?sputn@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEHPBDH@Z) already defined in msvcprtd.lib(MSVCP90D.dll)
Build log was saved at "file://c:\Documents and Settings\XP\My Documents\Quadratic solver\Quadratic solver\Debug\BuildLog.htm"
Quadratic solver - 23 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I did a clean on the project and it now works for multi-threaded debug, but I still get some error messages when I build it as a multi-threaded. Never mind.

You should indent your code next time you post code.