Compilare: user.cpp: In function ‘int main()’: user.cpp:14:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[S[++dr]]++; ^ user.cpp:15:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (f[S[dr]] == 1) ^ user.cpp:23:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (f[S[st]] != 1) ^ user.cpp:24:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[S[st++]]--; ^ user.cpp:25:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[S[st++]]--; ^ user.cpp:6:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("teatru.in", "r", stdin); ^ user.cpp:7:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("teatru.out", "w", stdout); ^ user.cpp:9:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d ", &n, &k); ^ user.cpp:10:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S + 1); ^ user.cpp:30:3: warning: ‘s’ may be used uninitialized in this function [-Wmaybe-uninitialized] for (int i = s; i <= d; ++i) ^ /tmp/ccxklxq8.o: In function `main': user.cpp:(.text.startup+0x76): warning: the `gets' function is dangerous and should not be used.