Compilare: user.cpp: In function ‘int main()’: 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 ‘FILE* freopen(const char*, const char*, FILE*)’, 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:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result In file included from /usr/include/string.h:640, from /usr/include/c++/4.4/cstring:45, from user.cpp:2: In function ‘void* memset(void*, int, size_t)’, inlined from ‘int main()’ at user.cpp:21: /usr/include/bits/string3.h:86: warning: call to void* __builtin___memset_chk(void*, int, unsigned int, unsigned int) will always overflow destination buffer