codeblocks 输出与在线编译器不同

Question

简而言之，我应该有“ 1 2 3 4 5 6 7 8 9 10 ”。当在 CodeBlocks 而不是 0 中执行时，我得到随机数。但是当使用在线编译器编译时，我得到了预期的输出。哪个输出靠谱？在线还是 CodeblockIDE 的？如果需要的话还有链表练习的代码：创建，输入数据元素，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

问题出在您的代码逻辑上。好的输出是 Code::Blocks 一个。

问题出在 insertNode 函数中。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，第 0 个元素是在你的第一个循环的第一次迭代中找到的，之后不会有错误，因为 j = i - 1 = -1。永远不要在你的代码中编辑头部的数据。此外，每次调用 insertNode 函数时，您都会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。你应该改为写 :

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

此外，您必须更改主循环中的边界。确实，listLength returns 列表中元素的数量（这里是 10），但是索引不是从 1 bt 从 0 开始，这意味着你不能停在 10（因为有没有第 10 个节点）但在 9。因此你必须写：

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*/
}

还有一点与此问题无关，但无论如何您都必须更正：您的 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;
}

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