Compilare: user.cpp: In function ‘int main()’: user.cpp:26:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] lib[ al[i] ] = (char)(i + 'a'); ^ user.cpp:27:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] rev[ (char)(i + 'a') ] = al[i]; ^ user.cpp:31:63: warning: array subscript has type ‘char’ [-Wchar-subscripts] for( int j = 0; j < 5; ++j ) v[i][j] = lib[ v[i][j] ]; ^ user.cpp:44:65: warning: array subscript has type ‘char’ [-Wchar-subscripts] for( int j = 0; j < 5; ++j ) out << rev[ v[i][j] ]; ^