Compilare: user.cpp: In function ‘int main()’: user.cpp:47:26: warning: unused variable ‘w’ [-Wunused-variable] int n,i,j,k,cate,sol,w,xx,yy; ^ user.cpp:45:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in" , "r" , stdin); ^ user.cpp:46:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out" , "w" , stdout); ^ user.cpp:49:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:52:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &v[i].x, &v[i].y); ^ user.cpp:64:18: warning: ‘xx’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(xx!=0 && yy!=0) ^ user.cpp:64:27: warning: ‘yy’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(xx!=0 && yy!=0) ^