There are actually several ways of doing this. You should look for documentation on glob for one:

do_something($_) foreach (<*.swf>);
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You can use opendir, readdir, and closedir and use a regexp or other file-test operation against each file found to determine if it matches your criteria:

opendir FOO, $dir or die $@;
foreach (readdir FOO) {
    do_something($_) if /\.swf$/;
}
closedir FOO;
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Or, if you need to recurse into subdirectories, you should consider File::Find. I'll let the documentation at CPAN illuminate that one for you.