Lua table.concat

Question

Is there a way to use the arg 2 value of table.concat to represent the current table index?

eg:

 t = {}
 t[1] = "a"
 t[2] = "b"
 t[3] = "c"

 X = table.concat(t,"\n")

desired output of table concat (X):

 "1 a\n2 b\n3 c\n"

Answer 1

Simple answer : no.

table.concat is something really basic, and really fast.

So you should do it in a loop anyhow.

If you want to avoid excessive string concatenation you can do:

function concatIndexed(tab,template)
    template = template or '%d %s\n'
    local tt = {}
    for k,v in ipairs(tab) do
        tt[#tt+1]=template:format(k,v)
    end
    return table.concat(tt)
end
X = concatIndexed(t) -- and optionally specify a certain per item format
Y = concatIndexed(t,'custom format %3d %s\n')