Compilare: user.cpp: In function ‘int main()’: user.cpp:36:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] cat1[a[i]][0]++; ^ user.cpp:37:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] cat1[a[i]][i]=cat1[a[i]][0]; ^ user.cpp:37:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] cat1[a[i]][i]=cat1[a[i]][0]; ^ user.cpp:38:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] A[a[i]][cat1[a[i]][0]]=i; ^ user.cpp:38:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] A[a[i]][cat1[a[i]][0]]=i; ^ user.cpp:42:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] cat2[b[i]][0]++; ^ user.cpp:43:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] aux=cat2[b[i]][i]=cat2[b[i]][0]; ^ user.cpp:43:36: warning: array subscript has type ‘char’ [-Wchar-subscripts] aux=cat2[b[i]][i]=cat2[b[i]][0]; ^ user.cpp:44:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[i].first=A[b[i]][aux]; ^ user.cpp:29:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("swap.in","r",stdin); ^ user.cpp:30:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("swap.out","w",stdout); ^ user.cpp:31:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a+1); ^ user.cpp:32:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(b+1); ^ /tmp/ccnbyt9M.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.