Compilare: user.cpp: In function ‘int main()’: user.cpp:24:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<strlen(a)-1;j++) ^ user.cpp:33:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v.size();j++) ^ user.cpp:50:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ok==0&&j==v.size()&&s.empty()) ^