lua - Find all upper/lower/mixed combinations of a string -

i need game server using lua..

i able save combinations of name string can used with:

if exists (string) 

example:

abc_-123     abc_-123      abc_-123  abc_-123      abc_-123 

etc

in game numbers, letters , _ - . can used names.

(a_b-c, a-b.c, ab_8 ... etc) 

i understand logic don't know how code it:d

0-lower     1-upper 

then

000     001 

etc

you can use recursive generator. first parameter contains left part of string generated far, , second parameter remaining right part of original string.

function combinations(s1, s2)         if s2:len() > 0                 local c = s2:sub(1, 1)                 local l = c:lower()                 local u = c:upper()                 if l == u                         combinations(s1 .. c, s2:sub(2))                 else                         combinations(s1 .. l, s2:sub(2))                         combinations(s1 .. u, s2:sub(2))                 end         else                 print(s1)         end end 

so function called in way.

combinations("", "abc_-123") 

you have store intermediate results instead of printing them.