Re: Iterator question

[Philipp Janda <siffiejoe@...>]

Am 12.06.2013 05:21 schröbte meino.cramer@gmx.de:
> Hi,

Hi!

> is it possible (and how) to create an iterator with lua, which returns
> the [n]th _and_ the [n+1]th value of in array/table with each call?

Sure:

    local function ip2_iter( st, var )
      var = var+1
      local v1 = st[ var ]
      if v1 ~= nil then
        return var, v1, st[ var+1 ]
      end
    end

    local function ipairs2( t )
      return ip2_iter, t, 0
    end


    for i,v,w in ipairs2( { "a", "b", "c", "d" } ) do
      print( i, v, w )
    end


1	a	b
2	b	c
3	c	d
4	d	nil


If you don't want the index, you need to create a closure to remember 
the current index between iterator calls ...

> Thank you very much in advance for any help!
> Best regards,
> mcc

HTH,
Philipp