Compilare: user.cpp: In function ‘int main()’: user.cpp:9:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paralelogram2.in","r",stdin); ^ user.cpp:10:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paralelogram2.out","w",stdout); ^ user.cpp:12:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&T); ^ user.cpp:15:63: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=1;i<=4;i++) scanf("%lf %lf",&a[i].x,&a[i].y); ^