Compilare: user.cpp: In function ‘int64_t Code(const string&)’: user.cpp:17:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < s.size(); ++i) ^ user.cpp: In constructor ‘Sir::Sir(const string&)’: user.cpp:30:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < s.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:47:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= a.size(); ++i) ^ user.cpp:55:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = a.size() - 1; i < b.size(); ++i) { ^ user.cpp:66:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < match.size(); ++i) ^