Compilare: user.cpp: In function ‘void big_add(big_num&, const big_num&)’: user.cpp:19: warning: array subscript has type ‘char’ user.cpp:19: warning: array subscript has type ‘char’ user.cpp:19: warning: array subscript has type ‘char’ user.cpp: In function ‘void solve(char, char)’: user.cpp:29: warning: array subscript has type ‘char’ user.cpp:29: warning: array subscript has type ‘char’ user.cpp:29: warning: array subscript has type ‘char’ user.cpp:30: warning: array subscript has type ‘char’ user.cpp:30: warning: array subscript has type ‘char’ user.cpp:30: warning: array subscript has type ‘char’ user.cpp: In function ‘int main()’: user.cpp:50: warning: array subscript has type ‘char’ user.cpp:52: warning: array subscript has type ‘char’ user.cpp:39: warning: unused variable ‘j’ user.cpp:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result