Eroare de compilare: user.c: In function ‘A’: user.c:7:51: error: invalid operands to binary - (have ‘P’ and ‘P’) int A(const void *a,const void *b) { return *(P*)a-*(P*)b; } ^ user.c: In function ‘main’: user.c:14:11: error: ‘p’ undeclared (first use in this function) for(i=p=1;i;i+=(p=(i==n?-p:p))) { ^ user.c:14:11: note: each undeclared identifier is reported only once for each function it appears in user.c: In function ‘A’: user.c:7:1: warning: control reaches end of non-void function [-Wreturn-type] int A(const void *a,const void *b) { return *(P*)a-*(P*)b; } ^ user.c: In function ‘main’: user.c:10:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("infasuratoare.in","r",stdin),freopen("infasuratoare.out","w",stdout),scanf("%d",&n); ^ user.c:10:50: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("infasuratoare.in","r",stdin),freopen("infasuratoare.out","w",stdout),scanf("%d",&n); ^ user.c:10:88: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("infasuratoare.in","r",stdin),freopen("infasuratoare.out","w",stdout),scanf("%d",&n); ^ user.c:12:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf",&v[i].x,&v[i].y); ^