Lua: 'for' loop problems (string.gsub) - lua

Question

I'm making a lua script for custom encrypting a string, but I can't find a loop that substitutes the letter to a number correspondent to the alphabet table.
It must return something like this:
"hello"
> 8, 4, 12, 12, 15
That'll be the first part of the encryption proccess but I can't program such a loop, any help? (Script below:)
local text = "what"
local key = math.random(100000, 500000)
local pie = math.pi
local n = 26
local alpha = { a = 1, b = 2, c = 3, d = 4, e = 5, f = 6 , g = 7, h = 8, i = 9, j = 10,
k = 11, l = 12, m = 13, n = 14, o = 15, p = 16, q = 17, r = 18, s = 19, t = 20, u = 21, v = 22, w = 23, x = 24, y = 25, z = 26}
function enumerate(str)
return str:gsub("%l", function(c) return c.char(c:byte()-96) end):byte(1,-1)
end
UPDATE: New question, how do I return the numbers as:
46, 68, 46, 32, 4, 12, 18, 15, 23, 32, 15, 23, 5, 8
Instead of a string or with whitespaces:
"46 68 46 32 4 12 18 15 23 32 15 23 5 8"

Answer 1

You just have to collect each char on a table with explode + encode (see below) and then call unpack (or table.unpack) to get a tuple.
First explode:
function explode(str)
local ret = {}
for c in str:gmatch(".") do
table.insert(ret, c)
end
return ret
end
The encoding part can be done this way:
local BASE_CHAR = ("a"):byte()
function encode(c)
return c:byte() - BASE_CHAR + 1
end
Putting everything together:
unpack = unpack or table.unpack -- Handling lua 5.1 or higher
function enumerate(str) -- Keeping the original name
local exploded = {}
for i, c in ipairs(explode(str)) do
exploded[i] = encode(c)
end
return unpack(exploded)
end
And a test:
print(enumerate("test"))
Which yields the following result:
20 5 19 20
Note:
I prefer to keep results in table and only unpack if necessary. This way you can manipulate the table the way you want and it's more convenient than dealing with tuples:
function enumerate(str) -- Keeping the original name
local exploded = {}
for i, c in ipairs(explode(str)) do
exploded[i] = encode(c)
end
return exploded
end
print(unpack(enumerate("test")))
And if you want a string:
print(table.concat(enumerate("test"), ", "))
Hope this solves the problem