Compilare: user.cpp: In function ‘int main()’: user.cpp:22:8: warning: unused variable ‘i’ [-Wunused-variable] int n,i,x,d,e,nr=1; ^ user.cpp:22:10: warning: unused variable ‘x’ [-Wunused-variable] int n,i,x,d,e,nr=1; ^ user.cpp:20:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sum.in","r",stdin); ^ user.cpp:21:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sum.out","w",stdout); ^ user.cpp:24:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^