Unresolved externals when Vector1 = Vector 2

[ZeHgS]

Hello!

I have been burning my brain for the last three hours trying to understand why my code wouldn't compile because of linking problems. These are the errors:

Error	10	error LNK1120: 7 unresolved externals	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Debug\Helper.exe	Helper
Error	7	error LNK2001: unresolved external symbol "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Clickable.obj	Helper
Error	8	error LNK2001: unresolved external symbol "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\MenuItem.obj	Helper
Error	9	error LNK2019: unresolved external symbol "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ) referenced in function "public: __thiscall std::_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >::~_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >(void)" (??1?$_Vector_alloc@$0A@U?$_Vec_base_types@VMenuItem@@V?$allocator@VMenuItem@@@std@@@std@@@std@@$$FQAE@XZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Options.obj	Helper
Error	2	error LNK2020: unresolved token (0A000140) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\MenuItem.obj	Helper
Error	3	error LNK2020: unresolved token (0A000142) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Clickable.obj	Helper
Error	5	error LNK2020: unresolved token (0A000187) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\MenuItem.obj	Helper
Error	6	error LNK2020: unresolved token (0A000188) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Clickable.obj	Helper
Error	1	error LNK2028: unresolved token (0A000141) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ) referenced in function "public: __thiscall std::_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >::~_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >(void)" (??1?$_Vector_alloc@$0A@U?$_Vec_base_types@VMenuItem@@V?$allocator@VMenuItem@@@std@@@std@@@std@@$$FQAE@XZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Options.obj	Helper
Error	4	error LNK2028: unresolved token (0A000188) "extern "C" int __cdecl _CrtDbgReportW(int,wchar_t const *,int,wchar_t const *,wchar_t const *,...)" (?_CrtDbgReportW@@$$J0YAHHPB_WH00ZZ) referenced in function "public: __thiscall std::_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >::~_Vector_alloc<0,struct std::_Vec_base_types<class MenuItem,class std::allocator<class MenuItem> > >(void)" (??1?$_Vector_alloc@$0A@U?$_Vec_base_types@VMenuItem@@V?$allocator@VMenuItem@@@std@@@std@@@std@@$$FQAE@XZ)	C:\Users\Ze\Documents\Visual Studio 2012\Projects\Helper\Helper\Options.obj	Helper

I learned through google that usually a problem like that is caused by calling a function without a body. I couldn't find any function that had no body, so I commented out all files one by one to find where the problem was, and I found that it was a specific line in a Class called MenuItem, which inherits from a class called Clickable.

The line that caused the problem is the first one of my constructor

MenuItem(SDL_Rect Rect, SDL_Surface* Surface, vector<MenuItem> SubItems)  : Clickable(Rect, Surface)
	{
                //first I tried like this
                m_SubItems = SubItems;

                //then this
		vector<MenuItem>::iterator iter_beg = m_SubItems.begin();
		vector<MenuItem>::iterator iter_end = m_SubItems.end();
		m_SubItems.assign(iter_beg, iter_end);

                
		//also tried using an initializer list
	}

What could be the problem? When I comment everything out, it builds fine.

Also, at first I had the class constructor declaration separate from the definition, but I kept getting an error from the compiler complaining that there should be a curly bracket after this:

MenuItem(SDL_Rect Rect, SDL_Surface* Surface, vector<MenuItem> SubItems) : Clickable(Rect, Surface);

so I had to move the definition to the same place as the declaration in order to get rid of it. Is my syntax wrong?

Thanks a lot!

[Lowest0ne]

When you define a custom constructor, the compiler stops giving you the "default" default and copy constructors...

// Okay
class test
{
  public:
  int x;
};

int main(void)
{
  test first;
  first.x = 1234;

  test second(first);
  cout << second.x << std::endl;
  return 0;
}


// Not Okay
class test
{
  public:
  int x;

  test(int y) : x(y) {} // note that you do need braces
};

int main(void)
{
  test first;  // Error: no default constructor found

  test first(1234);

  test second(first);  // still works
  cout << second.x << std::endl;
  return 0;
}

You should be passing that vector by reference too.

[ZeHgS]

Thank you very much for your answer! I actually managed to solve it yesterday with a friend's help. The problem is that Visual Studio was thinking I was trying to build in debug mode, when I was actually trying to build in release mode (or something like that). What fixed it was going to Project > Properties > C/C++ and removing _DEBUG (or any variant of this, I don't remember exactly) from Preprocessor Definitions.

Also, about the issue of needing a bracket after the declaration, I learned that I can omit the initializer list from the declaration and have it on the definition instead, thus enabling me to separate definition and declaration.

[Lowest0ne]

Anything that can be done should be done in an initializer list.

The initializer list goes in the definition:

MyClass(int x);

MyClass(int x) : val(x) {}