Compilare: user.cpp: In function ‘int main()’: user.cpp:13:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[c] == s[c+1] && c < s.size() - 1) ^ user.cpp:15:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (c == s.size() - 1) ^ user.cpp:21:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; c < s.size() - 1;) ^ user.cpp:25:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[c] <= s[c+1] && c < s.size() - 1) ^ user.cpp:29:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[c] >= s[c+1] && c < s.size() - 1) ^ user.cpp:33:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; c < s.size() - 1;) ^ user.cpp:37:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[c] >= s[c+1] && c < s.size() - 1) ^ user.cpp:41:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[c] <= s[c+1] && c < s.size() - 1) ^