C语言 代码块输出与在线编译器不同

Question

总之，我应该有"1 2 3 4 5 6 7 8 9 10 "当在CodeBlocks中执行而不是0时，我正在获得随机数。但是当使用在线编译器编译时，我得到了预期的输出。哪个输出是可靠的?在线还是CodeblockIDE的?如果需要的话，这里有链表实践的代码:创建，输入数据元素，在指定点删除，最后输出结果。

#include <stdio.h>       
#include <stdlib.h>      
#include <malloc.h>     
typedef int DataType;    
typedef struct Node
{
DataType data;
struct Node *next;
} SLNode;
void ListInitiate(SLNode **head)        /* Initialization */
{
/* If there is memory space, apply the head node space and make the head pointer point to the head node */
if((*head = (SLNode *)malloc(sizeof(SLNode))) == NULL) exit(1);
(*head)->next = NULL;          /* set the last of the list as Null */
}

int ListLength(SLNode *head)     /* Get the size of the linked list */
{
SLNode *p = head;             
int size = 1;
while(p->next != NULL)         /*count with loop*/
{
p = p->next;
size ++;
}
return size;
}
int ListInsert(SLNode *head, int i, DataType x)
/* Insert a node that contains the data element x before the node ai (0 ≤ i ≤ size) of the linked list with header */
{
SLNode *p, *q;
int j;
p = head;             /* p points to the head*/
j = -1;               /* the initial value of j is -1*/
while(p->next != NULL && j < i - 1)
/* Finally let pointer p point to data element ai-1 node */
{
p = p->next;
j++;
}
if(j != i - 1)
{
printf("Insert position parameter wrong!");
return 0;
}
/* q points to the new node*/
if((q = (SLNode *)malloc(sizeof(SLNode))) == NULL) exit(1);
q->data = x;
/* There is an error blow*/
q->next = p->next;
p->next = q;
return 1;
}
int ListDelete(SLNode *head, int i, DataType *x)
/* delete the node ai of the list with a header*/
/* put the data element of the node in x. If success, return 1; if fail, return 0*/
{
SLNode *p, *s;
int j;
p = head;
j = -1;
while(p->next != NULL && p->next->next!= NULL && j < i - 1)
/*Finally let pointer p point to data element ai-1 node */
{
p = p->next;
j++;
}
if(j!= i - 1)
{
printf("Insert position parameter wrong!");
return 0;
}

s = p->next;         /*s points to ai*/
*x = s->data; /*Assign the data field value of the node pointed by pointer s to x */
p->next = s->next;     /* delete ai*/
free(s);          /* free the memory space of s */
return 1;
}
int ListGet(SLNode *head, int i, DataType *x)
/*The function of taking the data element ai is similar to deleting ai function, but do not delete the data element ai node*/
{
SLNode *p;
int j;
p = head;
j = 0;
while(p->next != NULL && j < i)
{
p = p->next;
j++;
}
if(j != i)
{
printf("The position of the parameter is wrong!");
return 0;
}

*x = p->data;
return 1;
}
void Destroy(SLNode **head)
{
SLNode *p, *p1;
p = *head;
while(p != NULL)
{
p1 = p;
p = p->next;
free(p1);
}
*head = NULL;
}
void main(void)
{
SLNode *head;
int i , x;
ListInitiate(&head);
for(i = 0; i < 10; i++)
{
if(ListInsert(head, i, i+1) == 0)      /*insert ten data elements*/
{
printf("Error!! n");
return;
}
}
if(ListDelete(head, 4, &x) == 0)     /* delete data element 5*/
{
printf("error! n");
return;
}
for(i = 0; i < ListLength(head); i++)
{
if(ListGet(head, i, &x) == 0)      /* take out the element*/
{
printf("Error! n");
return;
}
else printf("%d    ", x);        /* show data elements*/
}
Destroy(&head);
}

Answer 1

问题出在代码的逻辑上。好的输出是Code::Blocks one。

问题在insertNode函数内。它的行为如下:它找到第i-1个节点并在它之后创建一个新节点。如果i = 0，在第一个循环的第一次迭代中找到了第0个元素之后就不会有错误了，因为j = i - 1 = -1。永远不要在代码中编辑头部的数据。此外，每次调用insertNode函数时，都要求新节点的值为其位置+ 1。

所以你会得到这个:

----------       -----       -----
| random |  ---> | 1 |  ---> | 2 |  ---> etc.
----------       -----       -----
head            0th         1st

之后，在listGet函数中，您对列表的制作方式产生了误解。例如，当调用listGet(head, 0, &x)时，条件p->next != NULL && j < i总是在第一次迭代时满足，这意味着返回的节点不是第0个，而是头。你应该这样写:

j = -1;  // 0 become -1
while(p->next != NULL && j < i)
{
p = p->next;
j++;
}

此外，必须在main中更改循环的边界。实际上，listLength返回列表中元素的数量(这里是10)，但是索引不是从1开始，而是从0开始，这意味着您不能在10处停止(因为没有第10个节点)，而是在9处停止。因此你必须这样写:

for(i = 0; i < ListLength(head) - 1; i++)
{
if(ListGet(head, i, &x) == 0)      /* take out the element*/
{
printf("Error! n");
return 1;
}
else printf("%d    ", x);        /* show data elements*/
}

还有一点与这个问题无关，但你必须纠正:你的destroy函数。

void Destroy(SLNode **head)
{
SLNode *p, *p1;
p = *head;
while(p != NULL)
{
p1 = p;
p = p->next;

/* make NULL assignment here */
p1->next = NULL;

free(p1);
}
/* head has been already freed in the above loop
*  do not try to manipulate it */
// *head = NULL;
}