Compilare: user.cpp: In function ‘int main()’: user.cpp:17:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size(),j<b.size();++i,++j) ^ user.cpp:17:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size(),j<b.size();++i,++j) ^ user.cpp:17:22: warning: value computed is not used [-Wunused-value] for(int i=0,j=0;i<a.size(),j<b.size();++i,++j) ^