How to print nested table using recursion in lua?

I want to print this table using recursion and not by using for loop. I am trying to avoid repeating code.

local t = {x=0, y=5, other={10,10,10,11}}

function DeepPrint (t)
  local request_headers_all = ""
  for k, v in pairs(t) do
    if type(v) == "table" then
      for k1, v1 in pairs(v) do
        local rowtext = ""
        rowtext = string.format("[%s %s] ",k, v1)
        request_headers_all = request_headers_all .. rowtext
      end 
    else
      local rowtext = ""
      rowtext = string.format("[%s %s] ", k, v)
      request_headers_all = request_headers_all .. rowtext
    end
  end
  return request_headers_all
end

print(DeepPrint (t))

Expected output (order doesn’t matter):

[y 5] [x 0] [other 10] [other 10] [other 10] [other 11]

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>Solution :

You can simply remove the inner loop and make a call to DeepPrint again using the value of v – the table:

local t = {x=0, y=5, other={10,10,10,11}}

function DeepPrint (t)
  local request_headers_all = ""
  for k, v in pairs(t) do
    if type(v) == "table" then
      request_headers_all = request_headers_all .. "[" .. k .. " " .. DeepPrint(v) .. "] "
    else
      local rowtext = ""
      rowtext = string.format("[%s %s] ", k, v)
      request_headers_all = request_headers_all .. rowtext
    end
  end
  return request_headers_all
end

print(DeepPrint (t))

Produces:

[y 5] [x 0] [other [1 10] [2 10] [3 10] [4 11] ] 

Note that you are not going to get these in order. Hashes are unordered, so you cannot guarantee that x will precede y will precede other.

Update: Strip out array indices for pure arrays:

local t = {x=0, y=5, other={10,10,10,11}}

function DeepPrint (t)
  local request_headers_all = ""
  for k, v in pairs(t) do
    if type(v) == "table" then
      request_headers_all = request_headers_all .. "[" .. k .. " " .. DeepPrint(v) .. "] "
    else
      local rowtext = ""
      if type(k) == "string" then
        rowtext = string.format("[%s %s] ", k, v)
      else
        rowtext = string.format("[%s] ", v)
      end    
      request_headers_all = request_headers_all .. rowtext
    end
  end
  return request_headers_all
end

Output:

[y 5] [x 0] [other [10] [10] [10] [11] ]