File appending

This is a discussion on File appending within the C Programming forums, part of the General Programming Boards category; Hello! I had a question about appending data in to a file. My program flows in the following way-- Code: ...

  1. #1
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    File appending

    Hello!

    I had a question about appending data in to a file.

    My program flows in the following way--
    Code:
    // This function reads data from the file
    parse_input_data_for_one_algo(some parameters) 
    {
    FILE *f = fopen (filename, "rw+");
    while ( fgets (in_line, 100, f) != NULL )
    {
    //read values
    }
    fclose(f);
    }
    Code:
    parse_input_data_for_second_algo(some parameters) 
    {
    FILE *f = fopen (filename, "rw+");
    while ( fgets (in_line, 100, f) != NULL )
    {
    //read values
    }
    fclose(f);
    }
    Code:
    // Call to both parse functions in another file which contains the main program
    int main(int argc, char **argv)
    {
    char *filename = argv [1];
    parse_input_data_for_one_algo (filename,some parameters);
    //Algorithm-1
    char *filename1 = argv [1];
    parse_input_data_for_second_algo (filename1,some parameters);
    //Algorithm-2
    }
    My text file is in the following format--

    x 12 44
    y 3 1
    y 1 2 -1
    z 1 2 1
    z 3 1 2
    z 4 1 3
    z 6 1 4
    t 1 2 1 2 1
    t 1 2 3 1 2
    t 1 3 4 1 1
    I am trying to write additional data from the main file after "Algorithm-1" is solved, in to the text file after all the "z" s

    So my new text file with appended data would look like this --
    (1,2,6,9 have been appended to the file)
    x 12 44
    y 3 1
    y 1 2 -1
    z 1 2 1 1
    z 3 1 2 2
    z 4 1 3 6
    z 6 1 4 9
    t 1 2 1 2 1
    t 1 2 3 1 2
    t 1 3 4 1 1
    The new appended text file would now be read by parse_input_data_for_second_algo.
    Kindly let me know of alternatives of how I could solve this problem.

    Thanks in advance!

  2. #2
    Epy
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    AFAIK, you're stuck with basically writing a new file, deleting the old one and renaming the new one to match the old filename

  3. #3
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    TX
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    Read data from text file into a buffer; filter line that contains "z"; append main file data into buffer that holds the "z" line.

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