从双向链表中删除所有与给定字符串出现相同的节点

Question

我正在尝试删除给定字符串的所有出现。此代码删除一个节点，但所有其他节点都保留。我试图将它包装在一个while循环中，但仍然没有效果。

我也想知道，是否可以删除 struct 参数并仍然让它发生。我试图删除它并修改了代码，但我得到一个分段错误。感谢您提前回答。

void deleteNode(struct node** head, char* searchName) {

        struct node* current;
        for(current=*head; current; current = current->next){
            if (!strcmp(current->name, searchName))
            {
            if (current->next)
                current->next->prev = current->next;
                if (current->prev)
                current->prev->next = current->prev;
                if (current == *head)
                *head = current->next;
                current->prev = NULL;
                current->next = NULL;
                free(current);
                return;
                }
            }
    }

Answer 1

你的功能是错误的。例如这个 if 语句

 if (current->next)
            current->next->prev = current->next;

应该像这样重写

 if (current->next)
            current->next->prev = current->prev;
                                           ^^^^

函数可以通过以下方式声明和定义

void deleteNode( struct node **head, const char *searchName )
{
    while ( *head )
    {
        if ( strcmp( ( *head )->name, searchName ) == 0 )
        {
            struct node *current = *head;
            if ( current->next ) current->next->prev = current->prev;
            *head = current->next;
            
            free( current );
        }
        else
        {
            head = &( *head )->next;
        }
    }
}

注意，如果结构体struct node的数据成员name指向一个动态分配的存储字符串的内存，那么在为上述函数中的指针current调用函数free之前，你必须释放为字符串分配的内存。那就是你需要再调用一个函数freelike

free( current->name );
free( current );

如果你有一个指向头节点的全局指针，例如head，那么该函数可以通过以下方式定义

void deleteNode( const char *searchName )
{
    struct node **head_ref = &head;

    while ( *head_ref )
    {
        if ( strcmp( ( *head_ref )->name, searchName ) == 0 )
        {
            struct node *current = *head_ref;
            if ( current->next ) current->next->prev = current->prev;
            *head_ref = current->next;
            
            free( current );
        }
        else
        {
            head_ref = &( *head_ref )->next;
        }
    }
}

Answer 2

return 语句将在第一次命中后结束函数。此外，序列current->next = NULL; free(current); current = current->next 将在释放内存后访问内存，并将 current 设置为 NULL。您可能需要在循环内更新current 并使用一个额外的节点指针变量进行删除。

void deleteNode(struct node** head, char* searchName)
{
    struct node* current;
    struct node* to_delete;
    for(current=*head; current;)
    {
        if (!strcmp(current->name, searchName))
        {
            to_delete = current;
            current = current->next;
            if (current) {
                current->prev = to_delete->prev;
            }
            if (to_delete->prev) {
                to_delete->prev->next = current;
            }
            if (to_delete == *head)
                *head = current;
            free(to_delete);
        } else {
            current = current->next;
        }
    }
}