当我在结构中使用STL字符串var时，调试断言失败 [英] Debug Assertion Failed when I use a STL string var in a struct

问题描述

当我读/写具有数据结构的二元文件时，会出现此错误(它具有字符串成员)

这是我的代码:

I have this error when I read/write binanry file with data are structs (it has string members)

this is my code:

//read data from file to linked list
int ReadFile(char* fname, Node* &head)
{
	Node* cur;
	BOOK a;
	ifstream iFile;
	iFile.open(fname, ios::binary);

	if(iFile.good() == 0)
		return 0;

	while( iFile.read((char*)&a, sizeof(a)) )
	{
		if (head==NULL)
		{
			head = new Node;
			head->data = a;
			head->pNext = NULL;
			cur = head;
		}
		else
		{
			cur->pNext = new Node;
			cur = cur->pNext;
			cur->data = a;
			cur->pNext = NULL;
		}
	}
	iFile.close();
	return 1;
}

//write data from LL to file
int WriteFile(char* fname, Node* head)
{
	Node* cur = head;
	ofstream oFile;
	oFile.open(fname, ios::binary);

	if(oFile.good() == 0)
		return 0;
	while(cur != NULL)
	{
		WriteNode(oFile, cur->data);
		cur = cur->pNext;
	}
	oFile.close();
	return 1;
}

//write one node
void WriteNode(ofstream& out, BOOK a)
{
	out.write((char*)&a, sizeof(a));
}

当我创建了data.bin文件来保存信息时.我在main()函数中调用ReadFile函数来读取数据.我得到了错误.

http://diendan.congdongcviet.com/attachment.php?attachmentid=8807&d=1331693026 [ ^ ]

这是我的结构:

when I have created data.bin file which save the info. I call ReadFile function in main() function to read data. I got the error.

http://diendan.congdongcviet.com/attachment.php?attachmentid=8807&d=1331693026[^]

this is my struct:

struct BOOK
{
    string isbn;        
    string bookname;    
    string genre;       
    string author;      
    string publisher;   
    int year;           
    int amount;         
};

struct Node
{
    BOOK data;
    Node* pNext;
};

那么如何解决这个问题呢?
谢谢！！
p/s:如何插入图像?

So how to solve this problem?
thank you!!
p/s: how to insert an image?

推荐答案

1.将Book *强制转换为char *是一件非常非常糟糕的事情.别.因此，按值将Book传递给函数WriteNode.许多复制构造函数在此处运行.
2.您不必插入图像:如果在打开消息框时按CTRL-C，则消息框中的文本将被复制到剪贴板.

最好的祝福，
Pablo.

1. Casting a Book * to a char * is a very, very bad thing. Don''t. So is passing a Book by value to function WriteNode. Lots of copy constructors running there.
2. You don''t have to insert an image: if you press CTRL-C when you have a message box open, the text in the message box gets copied to the clipboard.

Best wishes,
Pablo.

您应正确序列化 ["STL类的序列化" [

You should properly serialize[^] your struct. See, for instance: "Serialization of STL class"[^].

车轮，见面您的新发明家.开火，认识你的新发现者.

我知道您可能已经由一位讲师强加给您的这个烦人的小问题，他认为您必须从第一原理中学到如何编程C ++.但是，如果您使用的是字符串，那么为什么不花大量精力去使用标准库中的列表呢?

定义书籍后，创建清单非常简单:

std::list<book> my_books;

到此为止，所有被[1]丢弃的节点都放屁了.接下来是如何从文件中读取书籍并将其写入其中.读写只是复制，所以为什么不使用标准库中的复制算法呢?

编写它们:

Wheel, meet your new inventor. Fire, meet your new discoverer.

I know you''ve probably had this annoying little problem foisted on you by a lecturer that thinks you have to learn how to program C++ from first principles. However you''re using strings so why not go the whole hog and use a list from the standard library?

Once you''ve defined your books then creating a list is pretty simple:

std::list<book> my_books;

There you go, all the farting about with nodes disposed of [1]. Next up is how you read your books from a file and write them to it. Reading and writing is just copying so why not use the copy algorithm from the standard library?

To write them:

std::copy( my_books.begin(),
           my_books.end(),
           std::ostream_iterator<book>( file_stream ) );

阅读它们:

To read them:

std::copy( std::istream_iterator<book>( file_stream ),
           std::istream_iterator<book>(),
           std::back_inserter( my_books ) );

现在这里的草丛中有一条蛇...是的，您必须编写一些代码.您要做的就是为您的结构Book实现插入和提取运算符(<<>>).这样，您所有的代码都将像梦想一样工作.或一场噩梦:-).而且您将能够在不更改代码的情况下从控制台读取和写入书籍.

最后一件事-如果您可以聘请一位更好的C ++老师，那就去选一个.上个世纪以来，实施自己的清单是如此，任何让您自己编写清单的人都是施虐者.

干杯，

灰

[1]您现在可以开玩笑了:

编码器:我的代码没有节点"

评论者:闻起来如何?"

编码器:可怕！"

如果您不是讲英语的人并且错过了这个玩笑，请不要担心，除非您听过原著，甚至还算是有点可怜，否则它不是那么有趣.

Now there''s a snake in the grass here... Yep, you have to write some code. What you have to do is implement insertion and extraction operators (<< and >>) for your structure, Book. Then you all that code will work like a dream. Or a nightmare :-). And you''ll have the bonus of being able to read and write Books from the console with no code changes.

One final thing - if you can get a better C++ teacher go and get one. Implementing your own lists is so last century and anyone that''s making you write your own is a sadist.

Cheers,

Ash

[1] You can now make the joke:

Coder: "My code has no nodes"

Reviewer: "How does it smell?"

Coder: "Terrible!"

If you''re not a native English speaker and miss the joke, don''t worry, it ain''t that funny unless you''ve heard the original and even then it''s a bit poor.

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