Compilare: user.cpp: In function ‘void add(Node*, char*)’: user.cpp:25:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(node->v[c]==0){ ^ user.cpp:26:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] node->v[c]=new Node; ^ user.cpp:29:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] add(node->v[c],s+1); ^ user.cpp: In function ‘int main()’: user.cpp:34:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in","r",stdin); ^ user.cpp:35:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out","w",stdout); ^ user.cpp:36:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&N); ^ user.cpp:38:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccR7CzNm.o: In function `main': user.cpp:(.text.startup+0x7b): warning: the `gets' function is dangerous and should not be used.