Compilare: user.cpp: In function ‘void preproc()’: user.cpp:32:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] preva[0][a[0]]=0; ^ user.cpp:36:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] preva[i][a[i]]=i; ^ user.cpp:38:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] prevb[0][b[0]]=0; ^ user.cpp:42:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] prevb[i][b[i]]=i; ^