Question

C++链表输出有问题，有两个数字乱码，请求大神说明原因

#include <iostream>
using namespace std;

typedef struct Snake1
{
int xlefts;
int ytops;
int xrights;
int ybottoms;
static int node;
int direction;
int life;
Snake1 *next;
}Snake,*ListSnake;

int Snake::node=0;

ListSnake head;

void ShowNode(ListSnake head)
{
ListSnake p;
p=head;
cout<<p->node<<endl;
while (p!=NULL)
{
cout<<p->xlefts<<","<<p->ytops;
cout<<","<<p->xrights<<","<<p->ybottoms<<endl;
p=p->next;
}

}

ListSnake CreateSnake(ListSnake head)
{
ListSnake p,q;
head=new Snake;
head->xlefts=320;
head->ytops=60;
head->xrights=head->xlefts+10;
head->ybottoms=head->ytops+10;
++(head->node);
p=new Snake;
cout<<head->xlefts<<endl;
p->xlefts=head->xlefts+10;
cout<<p->xlefts<<endl;
p->ytops=head->ytops+10;
p->xrights=p->xrights+10;
p->ybottoms=p->ytops+10;
head->next=p;
q=p;
++(head->node);
p=new Snake;
p->xlefts=q->xlefts+10;
p->ytops=q->ytops+10;
p->xrights=p->xrights+10;
p->ybottoms=p->ytops+10;
q->next=p;
p->next=NULL;
++(head->node);
return head;
}

int main()
{
head=CreateSnake(head);
ShowNode(head);
return 0;
}

Answer 1

#include <iostream>
using namespace std;

typedef struct Snake1
{
int xlefts;
int ytops;
int xrights;
int ybottoms;
static int node;
int direction;
int life;
Snake1 *next;
}Snake,*ListSnake;

int Snake::node=0;

ListSnake head;

void ShowNode(ListSnake head)
{
ListSnake p;
p=head;
cout<<p->node<<endl;
while (p!=NULL)
{
cout<<p->xlefts<<","<<p->ytops;
cout<<","<<p->xrights<<","<<p->ybottoms<<endl;
p=p->next;
}
}

ListSnake CreateSnake(ListSnake head)
{
ListSnake p,q;

head=new Snake;
head->xlefts=320;
head->ytops=60;
head->xrights=head->xlefts+10;
head->ybottoms=head->ytops+10;

++(head->node);

p=new Snake;
cout<<head->xlefts<<endl;
p->xlefts=head->xlefts+10;
cout<<p->xlefts<<endl;
p->ytops=head->ytops+10;
p->xrights=p->xlefts+10; //这里写错了，你把p->xlefts写成p->xrights了
p->ybottoms=p->ytops+10;
head->next=p;

q=p;
++(head->node);

p=new Snake;
p->xlefts=q->xlefts+10;
p->ytops=q->ytops+10;
p->xrights=p->xlefts+10; //这也一样
p->ybottoms=p->ytops+10;
q->next=p;
p->next=NULL;

++(head->node);

return head;
}

int main()
{
head=CreateSnake(head);
ShowNode(head);
return 0;
}

Answer 2

p=new Snake;
cout<<head->xlefts<<endl;
p->xlefts=head->xlefts+10;
//p->xrights=0;先给个初值
cout<<p->xlefts<<endl;
p->ytops=head->ytops+10;
p->xrights=p->xrights+10;//这里p->xrights未设置初值，编译器会给个随机值。。。

p=new Snake;
p->xlefts=q->xlefts+10;
p->ytops=q->ytops+10;
p->xrights=p->xrights+10;//同上