Compilare: user.cpp: In function ‘void form_t(std::vector<int, std::allocator<int> >&, std::string)’: user.cpp:12: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:38: warning: comparison between signed and unsigned integer expressions user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp:50: warning: comparison between signed and unsigned integer expressions user.cpp:61: warning: comparison between signed and unsigned integer expressions