Compilare: user.cpp: In function ‘void insert(std::string)’: user.cpp:23:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < w.size(); ++i){ ^ user.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == w.size() - 1) ^ user.cpp: In function ‘void del(std::string)’: user.cpp:46:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < w.size(); ++i){ ^ user.cpp:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == w.size()-1) ^ user.cpp: In function ‘int num(std::string)’: user.cpp:70:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < w.size(); ++i){ ^ user.cpp: In function ‘int lung(std::string)’: user.cpp:85:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < w.size(); ++i){ ^