You can check the filename with a grep:

opendir(DIR, $somedir) or die "can't open $somedir for read: $!\n";
@files_i_want = grep { /^example\d(?:\.\d)*\.txt$/ } readdir DIR;
closedir(DIR) or die "error closing $somedir: $!\n";
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Then use @files_i_want as desired.

--sacked