Compilare: user.cpp: In function 'void back()': user.cpp:11: warning: array subscript has type 'char' user.cpp: In function 'int main()': user.cpp:36: warning: array subscript has type 'char' user.cpp:49: warning: array subscript has type 'char' user.cpp:62: warning: array subscript has type 'char' user.cpp:75: warning: array subscript has type 'char' user.cpp:88: warning: array subscript has type 'char'