Listing a directory using prefixes

Hello,

Is there any way to list the contents of a directory but using prefixes? For example:

If the directory contains files by the names:

a.txt

ab.txt

b.txt

Then I would like a list of all files starting with "a". I could not find any such examples in the documentation. Also I am interested in a solution for namespace interface rather than the object interface.

Thanks,

Gautam