Visual C++ cannot compile vector insert() - c++

Question

C++ newbie here. I've finished doing a project using Bloodshed Dev C++ and now I want to make it into a Visual C++ project because I want to learn how to use OpenGL in it and most tutorials use the later for demonstration.
Although unfamiliar with it, I have used a vector to manage a dynamic array of pointers to objects, which led me to using insert() and erase() without having any knowledge of iterators at all so don't be harsh with my question. The problem is the line where I insert a new item in vector using a calculated int to specify the position to be inserted (although I'm fairly sure that's not what's causing the compiler error -> see end of post). The line is (from here on I have replaced actual names with examples):
vectorExample.insert(vectorExample.begin() + position, NULL);
Everything compiles and works without any problem in Dev C++ but in Visual C++ when I try to compile this line I get the following errors (it compiles without it and program works for everything else):
1>c:\program files\microsoft visual studio 10.0\vc\include\xmemory(208): error C2440: 'initializing' : cannot convert from 'int' to 'ClassExample *'
1> Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
1> c:\program files\microsoft visual studio 10.0\vc\include\xmemory(280) : see reference to function template instantiation 'void std::allocator<_Ty>::construct<int>(ClassExample **,_Other &&)' being compiled
1> with
1> [
1> _Ty=ClassExample *,
1> _Other=int
1> ]
1> c:\program files\microsoft visual studio 10.0\vc\include\vector(668) : see reference to function template instantiation 'void std::_Cons_val<std::allocator<_Ty>,ClassExample*,int>(_Alloc &,_Ty1 *,_Ty2 &&)' being compiled
1> with
1> [
1> _Ty=ClassExample *,
1> _Alloc=std::allocator<ClassExample *>,
1> _Ty1=ClassExample *,
1> _Ty2=int
1> ]
1> c:\program files\microsoft visual studio 10.0\vc\include\vector(688) : see reference to function template instantiation 'void std::vector<_Ty>::emplace_back<int>(_Valty &&)' being compiled
1> with
1> [
1> _Ty=ClassExample *,
1> _Valty=int
1> ]
1> c:\program files\microsoft visual studio 10.0\vc\include\vector(675) : see reference to function template instantiation 'std::_Vector_iterator<_Myvec> std::vector<_Ty>::emplace<int>(std::_Vector_const_iterator<_Myvec>,_Valty &&)' being compiled
1> with
1> [
1> _Myvec=std::_Vector_val<ClassExample *,std::allocator<ClassExample *>>,
1> _Ty=ClassExample *,
1> _Valty=int
1> ]
1> c:\users\user\desktop\mycppproject\mycppfile.cpp(412) : see reference to function template instantiation 'std::_Vector_iterator<_Myvec> std::vector<_Ty>::insert<int>(std::_Vector_const_iterator<_Myvec>,_Valty &&)' being compiled
1> with
1> [
1> _Myvec=std::_Vector_val<ClassExample *,std::allocator<ClassExample *>>,
1> _Ty=ClassExample *,
1> _Valty=int
1> ]
I have been looking at examples and searching for two days straight and I can't find anything similar to my problem. I also tried:
vectorExample.insert(vectorExample.begin(), NULL);
but I still get the exact same errors. Am I doing something wrong?

Answer 1

Try to use
vectorExample.insert(vectorExample.begin() + position, nullptr);
In C++ NULL is defined as 0. So the template function can not convert int to a pointer.

Answer 2

I'll give it a shot.
If you look at the definition of NULL, it is just 0 or 0L. However, your vector accepts the type ClassExample *. While a pointer is essentially an int, you can't just put in an int. And NULL is just that, an int.
To fix this, I believe you could do something like:
ClassExample* p = NULL; //assigning a pointer to NULL (0) is alright
vectorExample.insert(vectorExample.begin() + position, p);

Answer 3

NULL is a define that maps to 0. The compiler is telling you that it cannot implicitly convert an integer to a pointer:
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
So do what the compiler tells you to do:
vectorExample.insert(vectorExample.begin() + position, reinterpret_cast<ClassExample*>(NULL));
Or:
vectorExample.insert(vectorExample.begin() + position, (ClassExample*)NULL);