/*若栈不空,删除S的栈顶元素,用e返回其值,并返回OK,否则返回ERROR*/
Status Pop(LinkStack *S, SElemType *e)
{
LinkStackPtr p;
if (StackEmpty(*S))
return ERROR;
*e = S->top->data;
p = S->top; /*将栈顶结点赋值给p*/
S->top = S->top->next; /*使得栈顶指针下移一位,指向后移结点*/
free(p); /*释放结点p*/
S->count--;
return OK;
}