Error

g++    -c -g -MMD -MP -MF "build/Debug/Cygwin-Windows/main.o.d" -o build/Debug/Cygwin-Windows/main.o main.cpp
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:71:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Iter_equals_val<_Value>::operator()(_Iterator) [with _Iterator = __gnu_cxx::__normal_iterator<Proizvod*, std::vector<Proizvod> >; _Value = const Proizvod]':
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algo.h:120:22:   required from '_RandomAccessIterator std::__find_if(_RandomAccessIterator, _RandomAccessIterator, _Predicate, std::random_access_iterator_tag) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Proizvod*, std::vector<Proizvod> >; _Predicate = __gnu_cxx::__ops::_Iter_equals_val<const Proizvod>]'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algo.h:162:43:   required from '_Iterator std::__find_if(_Iterator, _Iterator, _Predicate) [with _Iterator = __gnu_cxx::__normal_iterator<Proizvod*, std::vector<Proizvod> >; _Predicate = __gnu_cxx::__ops::_Iter_equals_val<const Proizvod>]'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algo.h:3779:50:   required from '_IIter std::find(_IIter, _IIter, const _Tp&) [with _IIter = __gnu_cxx::__normal_iterator<Proizvod*, std::vector<Proizvod> >; _Tp = Proizvod]'
main.cpp:64:66:   required from here
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h:191:17: error: no match for 'operator==' (operand types are 'Proizvod' and 'const Proizvod')
  { return *__it == _M_value; }
                 ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h:191:17: note: candidates are:
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:67:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_iterator.h:823:5: note: template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_IteratorL, _Container>&, const __gnu_cxx::__normal_iterator<_IteratorR, _Container>&)
     operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
     ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_iterator.h:823:5: note:   template argument deduction/substitution failed:
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:71:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h:191:17: note:   'Proizvod' is not derived from 'const __gnu_cxx::__normal_iterator<_IteratorL, _Container>'
  { return *__it == _M_value; }
                 ^
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:67:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_iterator.h:830:5: note: template<class _Iterator, class _Container> bool __gnu_cxx::operator==(const __gnu_cxx::__normal_iterator<_Iterator, _Container>&, const __gnu_cxx::__normal_iterator<_Iterator, _Container>&)
     operator==(const __normal_iterator<_Iterator, _Container>& __lhs,
     ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_iterator.h:830:5: note:   template argument deduction/substitution failed:
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:71:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h:191:17: note:   'Proizvod' is not derived from 'const __gnu_cxx::__normal_iterator<_Iterator, _Container>'
  { return *__it == _M_value; }
                 ^
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/x86_64-pc-cygwin/bits/c++allocator.h:33:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/allocator.h:46,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/string:41,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/locale_classes.h:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/ios_base.h:41,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:42,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ext/new_allocator.h:139:5: note: template<class _Tp> bool __gnu_cxx::operator==(const __gnu_cxx::new_allocator<_Tp>&, const __gnu_cxx::new_allocator<_Tp>&)
     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
     ^
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ext/new_allocator.h:139:5: note:   template argument deduction/substitution failed:
In file included from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/stl_algobase.h:71:0,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/char_traits.h:39,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ios:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/ostream:38,
                 from /usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/iostream:39,
                 from main.cpp:15:
/usr/lib/gcc/x86_64-pc-cygwin/4.9.0/include/c++/bits/predefined_ops.h:191:17: note:   'Proizvod' is not derived from 'const __gnu_cxx::new_allocator<_Tp>'
  { return *__it == _M_value; }
                 ^
In file included from main.cpp:20:0:
Proizvod.h:44:18: note: bool operator==(Proizvod&, Proizvod&)
      friend bool operator==(Proizvod& a, Proizvod& b){
                  ^
Proizvod.h:44:18: note:   no known conversion for argument 2 from 'const Proizvod' to 'Proizvod&'
nbproject/Makefile-Debug.mk:72: recipe for target 'build/Debug/Cygwin-Windows/main.o' failed
make[2]: *** [build/Debug/Cygwin-Windows/main.o] Error 1
make[2]: Leaving directory '/cygdrive/c/Users/Myname/Documents/NetBeansProjects/CS323-DZ12-MyName'
nbproject/Makefile-Debug.mk:60: recipe for target '.build-conf' failed
make[1]: *** [.build-conf] Error 2
make[1]: Leaving directory '/cygdrive/c/Users/MyName/Documents/NetBeansProjects/CS323-DZ12-Myname'
nbproject/Makefile-impl.mk:39: recipe for target '.build-impl' failed
make: *** [.build-impl] Error 2