Compilare: user.cpp: In function ‘int main()’: user.cpp:13:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paralelogram.in", "r", stdin); ^ user.cpp:14:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("paralelogram.out", "w", stdout); ^ user.cpp:16:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:21:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] &x1, &y1, &x2, &y2, &x2, &y3, &x4, &y4); ^ user.cpp:6:18: warning: ‘x3’ may be used uninitialized in this function [-Wmaybe-uninitialized] return fabs((x1 - x2) / 2); ^ user.cpp:18:26: note: ‘x3’ was declared here double x1, y1, x2, y2, x3, y3, x4, y4; ^