Compilare: user.cpp: In member function ‘big_number<base> big_number<base>::operator-(big_number<base>&) const [with int base = 1000000000]’: user.cpp:62: instantiated from here user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp:62: instantiated from here user.cpp:18: warning: comparison between signed and unsigned integer expressions user.cpp: In member function ‘big_number<base>& big_number<base>::operator+=(const big_number<base>&) [with int base = 1000000000]’: user.cpp:62: instantiated from here user.cpp:26: warning: comparison between signed and unsigned integer expressions user.cpp:26: warning: comparison between signed and unsigned integer expressions user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp:29: warning: comparison between signed and unsigned integer expressions