有以下程序：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]);}程序运行后的输出结果是______。
A．8,2,3,4,5,6,7,1,
B．5,6,7,8,1,2,3,4,
C．1,2,3,4,5,6,7,8,
D．8,7,6,5,4,3,2,1,