file pointers + recursion = sore head

This is a discussion on file pointers + recursion = sore head within the C Programming forums, part of the General Programming Boards category; heres my little problem, i need to save some information to a file that is stored in a binary tree, ...

  1. #1
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    Unhappy file pointers + recursion = sore head

    heres my little problem, i need to save some information to a file that is stored in a binary tree, getting the information is not a problem, <gotta love recursion aint you>, now to the problem, the code for opening the file is within the function and obviously it keeps opening the file with every item from the binary tree, so whats the problem i hear you ask, well i've already got stuff in the file that i've loading into the program and when i save that stuff and some new stuff i want to be able to erase the contents and start from fresh, but with every pass with recursion the new info gets erased also, i cant put the file open routine outside of the function cause the function will still call it every time

    heres the code

    void saveContents(PTRnode* &root, char pathname[60])
    {
    FILE *fp; //file pointer

    int temp;
    if(root==NULL)
    {
    return;
    }
    else
    {
    fp = fopen(pathname, "w");
    fprintf(fp,"%s\n%s\n%d\n",root->data.artist, root->data.title, root->data.numberTracks);
    for(temp=1;temp<=root->data.numberTracks;temp++)
    {
    fprintf(fp,"%s\n",&root->data.SongList[temp]);
    }
    fclose(fp);
    saveContents(root->left, pathname);
    saveContents(root->right, pathname);
    }


    }


    i hope that made sense all that typing, hope someone can help me

    thanx in advance korbitz

  2. #2
    ATH0 quzah's Avatar
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    Simple, open the file first, and instead of passing 'path name', pass it the file pointer. Additionally, why are you using '&root' here? Anyway...

    void saveContents(PTRnode* root, FILE *fp )

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
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    hey that worked thanx mate

    on the &root thingy, i'm positive i tried the other way and it never worked properly so i use * &root and it works fine

    relatively inexperienced at c, but slowly getting there

  4. #4
    ATH0 quzah's Avatar
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    Assuming the following:

    typedef struct node {
    ...node stuff...
    } NODE;

    Then you can do the following:

    NODE *nptr; //pointer to a node

    Assuming the following function:

    void function( NODE *npt, FILE *fp )
    { ...stuff... }

    Then a function call:

    function( nptr, myFilePtr );


    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
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    i think that looks fimiliar to what i had before, but for the life of me i could not get the address of root and assign a NULL value to it, thats why i changed it, inexperience probably

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