Compilare: user.cpp: In function ‘void add(std::string*, int)’: user.cpp:57:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<s->length();i++) { ^ user.cpp:80:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<s->length();i++) { ^ user.cpp: In function ‘bool isInSet(std::string*)’: user.cpp:96:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<s->length();i++) { ^ user.cpp: In function ‘std::string* query(std::string*)’: user.cpp:107:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<q->length();i++) { ^ user.cpp: In function ‘void update(std::string*, int)’: user.cpp:118:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<s->length();i++) { ^ user.cpp:146:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<s->length();i++) { ^