Question

下面的程序不适用于更大的字符串，但它适用于小字符串。我不知道为什么sortedInsert函数没有占用字符串的全长。此程序中也没有使用字符串长度约束。

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

/* Link list node */

struct node

{

    char* pattern;

    struct node* next;

};

/* function to insert a new_node in a list. Note that this

*   function expects a pointer to head_ref as this can modify the

*     head of the input linked list (similar to push())*/

void sortedInsert(struct node** head_ref, struct node* new_node)

{

    struct node* current;

    /* Special case for the head end */

    if (*head_ref == NULL || (strcmp((*head_ref)->pattern ,new_node->pattern)> 0))

    {

        new_node->next = *head_ref;

        *head_ref = new_node;

    }

    else

    {

        /* Locate the node before the point of insertion */

        current = *head_ref;

        while (current->next!=NULL &&

               strcmp(current->next->pattern, new_node->pattern)< 0)

        {

            current = current->next;

        }

        new_node->next = current->next;

        current->next = new_node;

    }

}

/* BELOW FUNCTIONS ARE JUST UTILITY TO TEST sortedInsert */

/* A utility function to create a new node */

struct node *newNode( char * pattern)

{

    /* allocate node */

    struct node* new_node =

        (struct node*) malloc(sizeof(struct node));

      new_node->pattern = (char *)malloc(sizeof(pattern));

    /* put in the data  */

    strcpy(new_node->pattern , pattern);



    new_node->next =  NULL;

    return new_node;

}

/* Function to print linked list */

void printList(struct node *head)

{





   struct node *temp = head;

    while(temp != NULL)

    { 

         printf("\n%s", temp->pattern);

        temp = temp->next;

    }

}

/* Drier program to test count function*/

int main()

{

    /* Start with the empty list */

    struct node* head = NULL;

    struct node* new_node = newNode("a.b.c.d.e.f.g.h.h.j.k.l.m.n.o");

    sortedInsert(&head, new_node);

    new_node = newNode("a.b.c.de.f.g.h.j.k.l.m.t.y.u.k");

    sortedInsert(&head, new_node);

    new_node = newNode("a.b.c.d.ef.g.h.h.k.j.l.y.u.l.p");

    sortedInsert(&head, new_node);

    printf("\n Created Linked List\n");

    printList(head);



    return 0;

}

以上是上述程序的输出，可以看到意外的输出。输出：

创建链接列表

a.b.c.d.e.f。）

a.b.c.d.ef.g.h.h.k.j.l.y.u.l.p

a.b.c.de.f.g）

Answer 1

malloc(sizeof(pattern))

然后

strcpy(new_node->pattern , pattern);不正确。

更好，使用strlen()获取收到的字符串长度，然后分配内存，然后执行strcpy()或memcpy()复制已接收的字符串。

Answer 2

尝试下面的代码，它会工作。你必须传递字符串长度而不是字符串本身

    new_node->pattern = (char *)malloc(strlen(pattern)+1);

    /* put in the data  */

    memcpy(new_node->pattern , pattern,strlen(pattern)+1);

Answer 3

其他答案是正确的;但是，似乎有一个专用函数strdup来做你想做的事情：

// Incorrect code
new_node->pattern = (char *)malloc(sizeof(pattern));
strcpy(new_node->pattern , pattern);

// Correct code, provided by user2083356
new_node->pattern = (char *)malloc(strlen(pattern)+1);
memcpy(new_node->pattern , pattern,strlen(pattern)+1);

// Does the same; seems easier to type and understand; also handles errors
new_node->pattern = strdup(pattern);

插入不适用于较大尺寸的琴弦

3 个答案: