Compilare: user.cpp: In function ‘int main()’: user.cpp:15:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<=s.size()-1;i++) ^ user.cpp:19:95: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (((s[i-1]>='a'&&s[i-1]<='z')||(s[i-1]>='A'&&s[i-1]<='Z'))&&i>0&&i<s.size()-1) ^