Compilare: user.cpp: In function ‘int recursiv(int, int, int)’: user.cpp:15:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int d=n;d<=s.size();++d) ^ user.cpp: In function ‘int main()’: user.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<=s.size();++i) ^ user.cpp:66:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<=s.size();++i) ^