写链表二进制文件（C）的 [英] Writing a linked list to binary file(C)

问题描述

因此​​，我成立了一个链表，从文件中读取数据，做了一些计算和处理，现在我想将新列表存储到一个二进制文件。

So I have set up a linked list and read data from a file, done some calculation and manipulation and now I want to store the new list into a binary file.

下面是我的结构设置：

typedef struct Comp{
    char name[5];
    char node1[5], node2[5];
    float value;    //value
}ComponentType;

typedef struct ListNodeT{

    ComponentType Component;
    float voltage, power, current;
    struct ListNodeT *nextPtr;
}ListNodeType;

在一个单独的函数我试图写入一个文件：

In a separate function I am trying to write to a a file:

FILE *filePtr;

char fileName[13] = "SaveData.bin";
filePtr = fopen(fileName, "wb");
int index = 0;

while (CircuitData != NULL)
{
    fwrite(CircuitData, sizeof(ListNodeType), 1, filePtr);
    CircuitData = CircuitData->nextPtr;
    index++;
}

以上code未工作，所以现在我的问题是，使用单一FWRITE（CircuitData，sizeof的（ListNodeType），1，filePtr）我可以写入文件，或者我应该分开来写每个组件，如下所示：

The above code is not working so now my question is, can I write to the file using a single fwrite(CircuitData, sizeof(ListNodeType), 1, filePtr) or should I write each component separately as follows:

fwrite(CircuitData->Component.name, sizeof(CircuitData->Component.name), 1, filePtr);

我应该怎样做呢？我的第二个问题是，我怎么会再次读取该二进制文件回结构体？

How should I be doing this? My second question is, how would I read this binary file again back into the Struct?

推荐答案

那么，你将不能够在一个新的程序调用使用从文件指针值，所以你需要做的事情关于那个。你可以打印和零出指针之前进行复印;那么阅读时，你需要分配正确的指针值新分配的结构。

Well, you won't be able to use the pointer-values from a file in a new invocation of the program, so you'll need to do something about that. You could make a copy before printing and zero-out the pointer; then when reading, you'll need to assign the correct pointer values for the newly allocated structs.

我大概用递归函数读取它们。事情是这样的：

I'd probably read them with a recursive function. Something like this:

ListNodeType *read_list_from_file (FILE *fileptr) {
    ListNodeType node;
    ListNodeType *nodeptr;
    if (fread(&node, sizeof(node), 1, fileptr) == sizeof(node)) {
        nodeptr = malloc(sizeof(node));
        //TODO: handle malloc failure
        memcpy(nodeptr, &node, sizeof(node);
        nodeptr->nextPtr = read_list_from_file(fileptr);
        return nodeptr;
    } else {
        return NULL;
    }
}

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