Compilare: user.cpp: In function ‘int main()’: user.cpp:66: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:67: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:68: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:71: warning: ignoring return value of ‘char* gets(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 ‘void back()’ 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 /tmp/ccU1Ckpe.o: In function `main': user.cpp:(.text+0x448): warning: the `gets' function is dangerous and should not be used.