php数组：返回匹配元素

Question

 class Photos 
{
private $photos = array();

function add_photo($filename, $date, $lat, $long) 
{
  $this->photos[] = array('filename' => $filename, 'date' => $date, 'lat' => $lat,  'long' => $long);
    return $this;
}

function get_all() 
{
   return json_encode($this->photos);
}

function get_N($n) 
{
    return json_encode(array_slice($this->photos, 0, $n));
}

}

I would like another function in my class that returns some of the arrays with a certain date. The date is extracted from photos using the exif_read_data function. They look something liek this: 2011:04:01 16:12:23. The function that im looking for should return all the photos from a certain date. So i would like to know how i make the function return, for example, all photos with a datestamp looking like 2011:04:01 xx:xx:xx. Hope you understand what i mean. Thanks in advance!

Answer 1

This should do it:

class Photos 
{
    private $photos = array();

    function add_photo($filename, $date, $lat, $long) { /* ... */ }

    function get_all() { /* ... */ }

    function get_N($n) { /* ... */ }

    function get_by_date($date)
    {
        $result = array();

        foreach ($this->photos as $photo)
        {
            if (strpos($photo['date'], $date) === 0)
            {
                $result[] = $photo;
            }
        }

        return $result;
    }
}

Photos::get_by_date('2011:04:01');

You may also want to look at the array_filter() function.

---

function get_all_dates()
{
    $result = array();

    foreach ($this->photos as $photo)
    {
        $result[substr($photo['date'], 0, 10)] = null;
    }

    return array_keys($result);
}

---

function get_all_dates_with_count()
{
    $result = array();

    foreach ($this->photos as $photo)
    {
        $date = substr($photo['date'], 0, 10);

        if (empty($result[$date]))
        {
            $result[$date] = 0;
        }

        ++$result[$date];
    }

    return $result;
}