Question

I have is an array of markdown files like this:

$mdfiles = glob("content/*.txt", GLOB_NOSORT);

I want to sort the files by a certain line inside each of them.

An example file is:

File
====
line-one:
date: [number-to-sort]

The array of files is then sorted by [number-to-sort] in each file, which can be accessed by:

$file_array = file($mdfiles[*], FILE_IGNORE_NEW_LINES)
substr($file_array[*], 6);

Finally I would like to strip each content/ and .md from the array key values.

Answer 1

The code looked a lot smaller in my mind, but the resulting code is just three lines 🙂

$files = glob('content/*.txt', GLOB_NOSORT);
// sort the file array by date; see below
usort($files, 'by_file_date');
// strip the filename
$files = array_map('strip_filename', $files);

The 'by_file_date' function is declared later and basically uses the get_date function internally to perform the date “pulling” from the files. I’ve used preg_match based on the form you’ve shown to find the date value; I’ve assumed that date is an integer (i.e. sequence of digits). If not, let me know.

// pull date value from the file
// @todo this function can be optimized by keeping a static array of
//   files that have already been processed
function get_date($f)
{
    // match the date portion; i'm assuming it's an integer number
    if (preg_match('/^date:\s*(\d+)/', file_get_contents($f), $matches)) {
        return (int)$matches[1];
    }
    return 0;
}

function by_file_date($a, $b)
{
    // sort by date ASC
    return get_date($a) - get_date($b);
}

Finally, you need to strip the filename; Assuming you just want the file name and not the directory:

function strip_filename($f)
{
    // strip the directory portion
    return basename($f);
}

Not sure where .md came from, so you have to let me know on that one 🙂