Compilare: user.cpp: In function ‘bool check(std::string, std::string)’: user.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<a.size();++j) ^ user.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<b.size();++i) ^ user.cpp:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=1;j<a.size();++j) ^