Compilare: user.cpp: In function ‘int main()’: user.cpp:15:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i-1]<=s[i] && i<strlen(s)) ^ user.cpp:18:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(++i; i<strlen(s); i++) ^ user.cpp:25:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] {while (s[i-1]<=s[i] && i<strlen(s)) ^ user.cpp:34:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^