Compilare: user.cpp: In function ‘int main()’: user.cpp:41:18: warning: unused variable ‘x3’ [-Wunused-variable] double x1,x2,x3,x4,y1,y2,y3,y4; ^ user.cpp:41:21: warning: unused variable ‘x4’ [-Wunused-variable] double x1,x2,x3,x4,y1,y2,y3,y4; ^ user.cpp:41:30: warning: unused variable ‘y3’ [-Wunused-variable] double x1,x2,x3,x4,y1,y2,y3,y4; ^ user.cpp:41:33: warning: unused variable ‘y4’ [-Wunused-variable] double x1,x2,x3,x4,y1,y2,y3,y4; ^ user.cpp:39:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.in","r",stdin); ^ user.cpp:40:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.out","w",stdout); ^ user.cpp:44:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:47:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2); ^