Compilare: user.cpp: In function ‘int main()’: user.cpp:37:13: warning: unused variable ‘j’ [-Wunused-variable] int n,i,j; ^ user.cpp:38:18: warning: unused variable ‘xp’ [-Wunused-variable] double sum=0,xp=0,yp=0; ^ user.cpp:38:23: warning: unused variable ‘yp’ [-Wunused-variable] double sum=0,xp=0,yp=0; ^ user.cpp:35:33: 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:36:35: 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:42:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:44:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf",&ve[i].x,&ve[i].y); ^