关于链表删除节点及打印的两个错误

Question

//遍历一般线性表,删除位于键值为负节点之后的所有节点

#include
#include
#include
#include

struct example
{
int input;
struct example* next;
};
typedef struct example EXAMPLE;

void creat (EXAMPLE* head);
void remove (EXAMPLE* head);
void print (EXAMPLE* head);

int main (void)
{
EXAMPLE* head;

creat (head);

// print (head); 单独调用这个函数的话就不行，但是把源代码拷到creat中执行就行，为什么会这样?
remove(head); //这个函数有错误,但找不到哪里出错了
// print (head);

return 0;

}

//---------------creat-------------------
void creat (EXAMPLE* head)
{

EXAMPLE* p;
EXAMPLE* pre;
int      i;
int      n;

head = (EXAMPLE*)malloc(sizeof(EXAMPLE));

printf("n:  ");
scanf("%d",&n);

i = 1;
printf("input: ");
scanf("%d", &head->input);
i++;

pre = head;
for(;i <= n; i++)
{
    p = (EXAMPLE*)malloc(sizeof(EXAMPLE));
    printf("input: ");
    scanf("%d", &p->input);

    pre->next = p;
    p->next = NULL;
    pre = p;
}

//打印
p = head;
while(p)
{
    printf("%d\n",p->input);
    p = p->next;
}

return;

}

//-----------------remove-----------------
void remove (EXAMPLE* head)
{
EXAMPLE* p;
EXAMPLE* pon;
EXAMPLE* pre;

//确定pon的位置
if(head->input < 0)
{
    pon = head->next;
    head->next = NULL;
}

else
{
    p = head;
     while(1)
    {
         if((p->next)->input < 0)
         {
            pon  = p->next;
            p->next = NULL;
            break;
         }

        if(!(p->next))
        {
            pon = NULL;
            break;
        }
        p = p->next;
    }
    }

//删除pon(包含在内)之后的所有节点
pre = pon;
while(pre)
{
    pre = pon->next;
    free(pon);
    pon = pre;
}

//打印
p = head;
while(p)
{
    printf("%d\n",p->input);
    p = p->next;
}

return;

}

//------------print-----------------
void print (EXAMPLE* head)
{
EXAMPLE* p;

p = head;
while(p)
{
    printf("%d\n",p->input);
    p = p->next;
}

return;

}

Answer 1

第一，head指针的值要从 creat 函数中传出，参数必须要指向指针的指针。这是你 print 函数无效的原因，因为 head 指针的数值不对。