Compilare: user.c: In function ‘calc’: user.c:42:7: warning: array subscript has type ‘char’ [-Wchar-subscripts] next[prev[i]] = next[i]; ^ user.c:43:7: warning: array subscript has type ‘char’ [-Wchar-subscripts] prev[next[i]] = prev[i]; ^ user.c:44:7: warning: array subscript has type ‘char’ [-Wchar-subscripts] next[prev[l]] = next[l]; ^ user.c:57:9: warning: array subscript has type ‘char’ [-Wchar-subscripts] next[prev[i]] = next[i]; ^ user.c:58:9: warning: array subscript has type ‘char’ [-Wchar-subscripts] prev[next[i]] = prev[i]; ^ user.c: In function ‘main’: user.c:71:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d ", &n); ^ user.c:73:10: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Wunused-result] fgets(s, MAXL + 2, in); ^