Not sure if the sorting is the same. However, your code is broken and shouldn't run.

                                  v-- what's that @?
my @files = grep(/ap|ck_hm1_111/, @readdir(DIR))
[download]

Also, your regular expression needs to have the 'ap' and 'ck' grouped properly, or else you'll match a file called 'apples.txt'. If you want the files to be sorted alphabetically (let's assume lower case), you can stick in a sort block.

my @files = grep /(?:ap|ck)_hm1_111/, sort { lc $a cmp lc $b } readdir
+(DIR);
[download]

Cheers,
Ovid

Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.

my @files = glob("*_hm1_111");
[download]

readdir on the other hand is very fast, and returns you the files in whatever order they are stored in the internal representation for your file system. This will not always be alpha/ascii-betical. glob always returns files sorted ascii-betically.

The last difference between the two is how . (dot) files are handled. glob("*") will not return files such as .bashrc but readdir will. glob(".*") must be called if you want the . files. (In fact glob works very much like the UNIX c-shell.)

Having said all of this, I'd suggest you use ovid's suggestion in most circumstances. However, if it is likely that your directory contents will be very large (and you are only interested in a small fraction of the files) and if performance is important then I'd suggest you compare ovid's suggestion with something like this:

my @files = grep /^(?:ap|ck)_hm1_111/, glob("DIR/*_hm1_111");
[download]

Jacinta