Compilare: user.cpp: In function ‘int main()’: user.cpp:47:28: warning: NULL used in arithmetic [-Wpointer-arith] while (s[i]!=NULL) y=y*10+(s[i++]-'0'); ^ In file included from /usr/include/string.h:642:0, from /usr/include/c++/4.8/cstring:42, from user.cpp:3: In function ‘void* memset(void*, int, size_t)’, inlined from ‘int main()’ at user.cpp:48:29: /usr/include/i386-linux-gnu/bits/string3.h:85:70: warning: call to void* __builtin___memset_chk(void*, int, unsigned int, unsigned int) will always overflow destination buffer [enabled by default] return __builtin___memset_chk (__dest, __ch, __len, __bos0 (__dest)); ^