Compilare: user.cpp: In function ‘void multiply(char*, int)’: user.cpp:27:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] mare[++ mare[0] ] = t % base; ^ user.cpp: In function ‘int divide(char*, int)’: user.cpp:38:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!mare[mare[0]] && mare[0]) ^ user.cpp: In function ‘void subtract(char*, char*)’: user.cpp:64:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!a[a[0]] && a[0]) ^