正则表达式以匹配用短划线（-）分隔的数字并获取子字符串

Question

I have a lot of image files in a directory with their ID between some descriptions about what it contains.

This is an example of the files in that directory: de-te-mo-01-19-1084 moldura.JPG, ce-ld-ns-02-40-0453 senal.JPG, dp-bs-gu-01-43-1597-guante.JPG, am-ca-tw-04-30-2436 Tweter.JPG, am-ma-ac-02-26-0745 aceite.JPG, ca-cc-01-43-1427-F.jpg

What I want is to get the ID of the image * (nn-nn-nnnn) and rename the file with that sub-string.

*n as a number.

The result from the list above would be like: 01-19-1084.JPG, 02-40-0453.JPG, 01-43-1597.JPG, 04-30-2436.JPG, 02-26-0745.JPG, 01-43-1427.jpg .

This is the code I'm using to loop the directory:

 $dir = "images";

 // Open a known directory, and proceed to read its contents
 if (is_dir($dir)) {
    if ($dh = opendir($dir)) {
        while (($file = readdir($dh)) !== false) {
            if($sub_str = preg_match($patern, $file))
            {
                rename($dir.'/'.$file, $sub_str.'JPG');
            }
        }
        closedir($dh);
    }
 }

So, how my $patern would be to get what I want?

Answer 1

Wouldn't that be just like:

^.*([0-9]{2})-([0-9]{2})-([0-9]{4}).*\.jpg$

Explain:

^                      Start of string
.*                     Match any characters by any number 0+
([0-9]{2})             2 Digits
-                      Just a - char
([0-9]{2})             2 Digits
-                      Just a - char
([0-9]{4})             4 Digits
-                      Just a - char
.*                     Any character
\.jpg                  Extension and escape wildcard
$                      End of string

Now you got 3 groups inside the () . You have to use index 1, 2 and 3.

Answer 2

$pattern must be like this:

$pattern = "/^.*(\d{2}-\d{2}-\d{4}).*\.jpg$/i"

This pattern can check file name and get id as match group. Also preg_math return number, not string. Matches return as third param of function. while body must looks like this:

if(preg_match($patern, $file, $matches))
{
      rename($dir.'/'.$file, $matches[1].'.JPG');
}

$matches is array with matched string and groups.