Re: Reversing the order of a text file

At 12:55 PM 5/31/00 -0400, Brian C. Doyle wrote:

Hello,

        I have a file info.txt that is a list.  I want to read the file in reverse order.  How do i go about doing this?

Hi Brian, Here are some examples with lots of comments. Have fun! /*

        The file function reads in a file and generates an
        array from it.  Elements in the array will correspond
        to lines in the file.

        For Example: If you have a file that contains five
        lines:

                info.txt
                --------
                Hal             (555) 555-5555
                Alice   (555) 555-5555
                Peter   (555) 555-5555
                Pat             (555) 555-5555
                Yamuin  (555) 555-5555

        and you do this:

                $array = file ('info.txt')

        $array will look like this:

                $array[0] =     "Hal    (555) 555-5555";
                $array[1] =     "Alice  (555) 555-5555";
                $array[2] =     "Peter  (555) 555-5555";
                $array[3] =     "Pat    (555) 555-5555";
                $array[4] =     "Yamuin (555) 555-5555";

*/ $list = file ('info.txt'); /*

        The shortest way is to use the pop function inside
        a while loop.  Pop grabs removes the last element
        from the array and returns it.  Note that once you
        have looped through the array like this, it will be
        empty!

*/ while ($list) {

        print pop ($list) . '<br>';

} /*

        You can use count to find out the number of elements
        in your array, and then use a while loop to loop
        backwards through the elements.

        Keep in mind that the list array has five elements in
        it, however, the last index for the array is 4 - this is
        because the first index of the array is 0 - not 1.

*/ $list_length = count ($list); $current_index = $list_length - 1; while ($current_index != 0) {

        print $list[$current_index] . '<br>';

        # Decrease the value of $current_index by one
        --$current_index;

} /*

        You can use reverse on your array and use a while loop
        in combination with list and each.
        Give the documentation on each a good read before you
        start using it a lot.  It has a few surprises for
        beginners.  Each is also the best way to loop through
        arrays that contain non-numeric keys.

*/ $list = array_reverse ($list); while (list ($key) = each ($list)) {

        print $list[$key];

} Also, there are lots of different ways to do this - these are just a few to get you started. Good Luck! Zak Greant