Compilare: user.cpp: In function ‘int main()’: user.cpp:39:13: warning: unused variable ‘j’ [-Wunused-variable] int n,i,j; ^ user.cpp:40:21: warning: unused variable ‘xp’ [-Wunused-variable] long double sum=0,xp=0,yp=0; ^ user.cpp:40:26: warning: unused variable ‘yp’ [-Wunused-variable] long double sum=0,xp=0,yp=0; ^ user.cpp:37:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.in","r",stdin); ^ user.cpp:38:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.out","w",stdout); ^ user.cpp:45:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:48:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf",&x,&y); ^