单选题 下列程序的输出结果是( ). void f(int *x, int *y) { int t; t=*x,*x=*y;*y=t; } main( ) { int a[8]={1,2,3,4,5,6,7,8},i,*p,*q; p=a;q=&a[7]; while(p<q) { f(p,q); p+ +; q--;} for (i=0;i<8;i+) printf("%d,",a[i]); }