Compilare: user.cpp: In function ‘void cit()’: user.cpp:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:13: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void calc()’: user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void afis()’: user.cpp:36: warning: comparison between signed and unsigned integer expressions