c++ - VS2010: fatal error LNK1120: 1 unresolved externals . Working with templates -

have simple assignment classes , templates class, have searched on here , no solutions seem fix issue. when try compile, comes up:

1>msvcrtd.lib(crtexe.obj) : error lnk2019: unresolved external symbol _main referenced in function ___tmaincrtstartup 1>c:\users\leanne\documents\visual studio 2010\projects\partc\debug\partc.exe : fatal error lnk1120: 1 unresolved externals 

have console project using empty project. can me find issue? here code:

#include <iostream> using namespace std; template<typename itemtype> class vec3 {     itemtype x, y ,z; public:     vec3<itemtype>(){x=0;y=0;z=0;}     vec3<itemtype>(const vec3<itemtype>& other);     vec3<itemtype> operator+(vec3<itemtype>);     vec3<itemtype> operator-(vec3<itemtype>);     bool operator==(vec3<itemtype> other);     vec3<itemtype> operator=(vec3<itemtype>);     ~vec3<itemtype>(){;} }; template<typename itemtype> vec3<itemtype> vec3<itemtype>::operator+(vec3<itemtype> other) {     vec3 temp;     temp.x = x + other.x;     temp.y = y + other.y;     temp.z = z + other.z;     return temp; } template<typename itemtype> bool vec3<itemtype>::operator==(vec3<itemtype> other) {     if(x != other.x)         return false;     if(y != other.y)         return false;     if(z != other.z)         return false;     return true; } template<typename itemtype> vec3<itemtype> vec3<itemtype>::operator-(vec3<itemtype> other) {     vec3 temp;     temp.x = x - other.x;     temp.y = y - other.y;     temp.z = z - other.z;     return temp; }   template<typename itemtype> vec3<itemtype> vec3<itemtype>::operator=(vec3<itemtype> other) {     x = other.x;     y = other.y;     z = other.z;     return *this; } template<typename itemtype> vec3<itemtype>::vec3(const vec3<itemtype>& other) {     x = other.x;     y = other.y;     z= other.z; } template<typename itemtype> int main() {     vec3<int> v1;     vec3<int> v2(v1);     vec3<double> v3 = v2;     v3 = v1+v2;     v3 = v1-v2;     if(v1==v2)     {         return 0;     }     return 0;  }   

your getting error because made main template:

template<typename itemtype> int main() 

please remove template<typename itemtype>. main not allowed template.

once remove that, errors on vec3<double> v3 = v2; because v2 vec3<int> , cannot converted vec3<double>.