Compilare: user.cpp: In function ‘int main()’: user.cpp:17:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<b.length()-a.length();i++) ^ user.cpp:21:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<a.length();j++) ^ user.cpp:34:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<ap.size();i++) g << ap[i] << " "; ^