Compilare: user.cpp: In function ‘void add(std::string*, int)’: user.cpp:63:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s->length();i++) { ^ user.cpp:82:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s->length();i++) { ^ user.cpp: In function ‘bool isInSet(std::string*)’: user.cpp:99:28: 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:110:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<q->length();i++) { ^ user.cpp: In function ‘void update(std::string*, int)’: user.cpp:122:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s->length();i++) { ^ user.cpp:142:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s->length();i++) { ^