Compilare: user.cpp: In constructor ‘Big_Integer::Big_Integer(long long int)’: user.cpp:20:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] data[++data[0]] = x%10; ^ user.cpp: In member function ‘void Big_Integer::operator+=(Big_Integer&)’: user.cpp:63:43: warning: array subscript has type ‘char’ [-Wchar-subscripts] h.data[++h.data[0]] = (t += x.data[k] + data[j])%10; ^ user.cpp:73:43: warning: array subscript has type ‘char’ [-Wchar-subscripts] h.data[++h.data[0]] = (t += data[j])%10; ^ user.cpp:77:43: warning: array subscript has type ‘char’ [-Wchar-subscripts] h.data[++h.data[0]] = (t += x.data[k])%10; ^ user.cpp:80:39: warning: array subscript has type ‘char’ [-Wchar-subscripts] h.data[++h.data[0]] = t%10; ^