Compilare: user.cpp: In function ‘int main()’: user.cpp:67: warning: array subscript has type ‘char’ user.cpp:67: warning: array subscript has type ‘char’ user.cpp:18: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:19: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int op_not()’: user.cpp:126: warning: array subscript has type ‘char’