C / C++ / MFC

djgmad wrote:

Is there a specific way of writing/reading a linked list to and from a random access file in c++....if so could someone please give me an example

djgmad wrote:

Hope I'm not asking for much but is it possible for you to provide some examples please......thanks in advance.

#include <stdio.h>
#include <string.h>

typedef struct node
{
    char *text;
    int num;
    node *next;
};

void addNode(node* &listHead,char *newText, int newInt)
{
    node *curPos;

    curPos = listHead;
    if (curPos == NULL)
    {
        listHead = new node;
        curPos = listHead;
    }

    else
    {
        while (curPos->next != NULL)
            curPos = curPos->next;
        curPos->next = new node;
        curPos = curPos->next;
    }

    curPos->next = NULL;
    curPos->num = newInt;
    curPos->text = strdup(newText);
}

void dispList(node *firstNode)
{
    node *curNode;
    curNode = firstNode;

    while (curNode != NULL)
    {
        printf("Text: %s\n", curNode->text);
        printf("Num: %d\n", curNode->num);
        curNode = curNode->next;
        if (curNode)
            printf("\n");
    }
}

void saveListToFile(node *firstNode, char *szFilename)
{
    node *curNode;
    FILE *fp;
    char asciiNull = 0;
    int sLen;

    curNode = firstNode;
    fp = fopen(szFilename, "wb");

    while (curNode != NULL)
    {
        sLen = strlen(curNode->text);

        // write length of string (house keeping)
        fwrite(&sLen, sizeof(int), 1, fp);
        // write string (node member)
        fwrite(curNode->text, 1, sLen, fp);
        // write number (node member)
        fwrite(&curNode->num, sizeof(curNode->num), 1, fp);
        curNode = curNode->next;
    }
    fclose(fp);
}

node *loadListFromFile(char *szFilename)
{
    FILE *fp;
    node *result = NULL;
    char strBuffer[32];
    int intBuffer, sLen;
    char tmpChar;

    fp = fopen(szFilename, "rb");
    printf("filePos: %d\n", ftell(fp));

    fread(&sLen, sizeof(int), 1, fp);
    strBuffer[sLen] = 0;
    fread(strBuffer, 1, sLen, fp);
    fread(&intBuffer, sizeof(int), 1, fp);
    addNode(result, strBuffer, intBuffer);

    while (!feof(fp))
    {
        fread(&sLen, sizeof(int), 1, fp);
        strBuffer[sLen] = 0;
        fread(strBuffer, 1, sLen, fp);
        fread(&intBuffer, sizeof(int), 1, fp);
        addNode(result, strBuffer, intBuffer);
    }

    fclose(fp);

    return result;
}

int main()
{
    char buffer[32];
    int i;
    node *listHead, *loadedList;
    listHead = NULL;

    for (i=0; i<10; i++)
    {
        sprintf(buffer, "item_%d", i+1);
        addNode(listHead, buffer, i+1);
    }
    saveListToFile(listHead, "list.dat");
    loadedList = loadListFromFile("list.dat");

    printf("Created list:\n");
    dispList(listHead);

    printf("Loaded list:\n");
    dispList(loadedList);

    return 0;
}

djgmad wrote:

Is there a specific way of writing/reading a linked list to and from a random access file in c++....

siddharth0007 wrote:

c
link list implementation

siddharth0007 wrote:

See! (stands and points)
Link list implementation.

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