C语言程序简单题（初学指针）

#include<stdio.h>
int main()
{
int *p,*q,*r,i,j,a[10]={9,8,7,6,5,4,3,2,1,0};
int k=0;

for(k=0;k<10;k++)
printf("%d ",*(a+k));
printf("\n");
printf("input p [0<=p<=9]");
scanf("%d",&i);
printf("input q [p<q<=9]");
scanf("%d",&j); /*输入p和q p要小于q*/
p=a+i; /*p 和q 都应该在0到9之间*/
q=a+j;
r=a+(q-p)/2+1;
printf("*p=%d *q=%d *r=%d",*p,*q,*r);
getch();
return 0;
}

if(q>p)
r=p+(q-p)/2;
else
r=q+(p-q)/2;

unsigned i = (unsigned)p;
unsigned j = (unsigned)q;
unsigned k = j - i;
r = (int*)(i + k/2);

#include <stdio.h>
#include<stdlib.h>
int main()
{
int a[5]={0,1,2,3,4};
int *p,*q,*r;
p=&a[0];q=&a[2];
r=p+((q-p)/2);