Compilare: user.cpp: In function ‘void read_data()’: user.cpp:6: warning: unused variable ‘c’ user.cpp:8: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:9: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:12: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void roy_floyd()’: user.cpp:23: warning: suggest explicit braces to avoid ambiguous ‘else’ user.cpp: In function ‘void write_data()’: user.cpp:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result