Compilare: main.cpp: In function 'int main()': main.cpp:20:21: warning: passing NULL to non-pointer argument 1 of 'void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::value_type = int]' [-Wconversion-null] v.push_back(NULL); ^ main.cpp:24:24: warning: passing NULL to non-pointer argument 1 of 'void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::value_type = int]' [-Wconversion-null] nev.push_back(NULL); ^ main.cpp:31:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0; j<= nev.size()-1; j++) ~^~~~~~~~~~~~~~~ main.cpp:39:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (nev[j]<v.size()-1) main.cpp:49:20: warning: passing NULL to non-pointer argument 1 of 'void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; std::vector<_Tp, _Alloc>::value_type = int]' [-Wconversion-null] nev.push_back(NULL); ^