Comparing two index tables by index in lua

Question

I am trying to compare two tables of equal length with a function, since I do not know another way to do this. However, with the following function, it does not register, and I do not know why. I hope someone can clarify this problem or better compare these two tables.

The tables are populated with the following code:

str = "parameters determined by program (all digits)"
tableone = {}
for word in str:gmatch("%d") do table.insert(tableone,word) end

It is identical for both tables, except, of course, for the names of individual tables. Tables are filled in correctly and displayed correctly when I print them. Here are two tables for this question:

tableone = {}
tabletwo = {}
for i=1,4 do table.insert(tableone, i) end
for i=1,4 do table.insert(tabletwo, i) end

Obviously, these two tables will be equal to each other. The function I wrote to compare index tables is as follows:

function comparetables(t1, t2)
matchct = 0
 for i=1,#t1 do
    if t1[i] == t2[i] then
    matchct = matchct + 1
    end
if matchct == #t1 then
return true
end
end

I tried to do

print(comparetables(tableone,tabletwo))

, "true", . , , . . ? - table.compare, -, , , . !

:

mastermaind. , . , , , , .

• , , Ccount 1.
• , , Pcount 1

, {1, 3, 3, 4} {4, 4, 3, 1} Pcount 2 ( 4 1) Ccount 1 ( ). , , , 4 Pcount .

Answer 1

, , , - , lua OO.

- :

GameState = {}
GameState.mt = {}
GameState.mt.fns = {}
GameState.mt.__index =  GameState.mt.fns

function GameState.new(a,b,c,d)
-- TODO: put argument checks here...
  local retval = {}
  retval[1] = a
  retval[2] = b
  retval[3] = c
  retval[4] = d
  setmetatable(retval, GameState.mt)
  return retval
end

function GameState.mt.fns.print( self )
  print(" GameState: ", self[1], self[2], self[3], self[4] )
end

function GameState.mt.__tostring( self )
  return "GameState: "..self[1].." "..self[2].." "..self[3].." "..self[4]
end

function GameState.mt.__eq(self, other)
  -- Check it actually a GameState, and all its bits match
  return getmetatable(other)==GameState.mt and
    (self[1] == other[1]) and 
    (self[2] == other[2]) and 
    (self[3] == other[3]) and 
    (self[4] == other[4])
end

:

state1 = GameState.new(1,2,3,4)
state2 = GameState.new(1,2,3,4)

print("State 1 is:")
state1:print()

print("State 2 is:")
print(state2)

print( "state1 == state2 : ", state1 == state2 )

print( "Changing state 2") 
state2[1]=2

print( "state1 == state2 : ", state1 == state2 )

Answer 2

, :

function comparetables(t1, t2)
  if #t1 ~= #t2 then return false end
  for i=1,#t1 do
    if t1[i] ~= t2[i] then return false end
  end
  return true
end

: , .

-- This is not clever enough to find matching table keys
-- i.e. this will return false
--   recursive_compare( { [{}]:1 }, { [{}]:1 } )
-- but this is unusual enough for me not to care ;)
-- It can also get stuck in infinite loops if you use it on 
-- an evil table like this:
--     t = {}
--     t[1] = t

function recursive_compare(t1,t2)
  -- Use usual comparison first.
  if t1==t2 then return true end
  -- We only support non-default behavior for tables
  if (type(t1)~="table") then return false end
  -- They better have the same metatables
  local mt1 = getmetatable(t1)
  local mt2 = getmetatable(t2)
  if( not recursive_compare(mt1,mt2) ) then return false end

  -- Check each key-value pair
  -- We have to do this both ways in case we miss some.
  -- TODO: Could probably be smarter and not check those we've 
  -- already checked though!
  for k1,v1 in pairs(t1) do
    local v2 = t2[k1]
    if( not recursive_compare(v1,v2) ) then return false end
  end
  for k2,v2 in pairs(t2) do
    local v1 = t1[k2]
    if( not recursive_compare(v1,v2) ) then return false end
  end

  return true  
end

Here is a usage example:

print( recursive_compare( {1,2,3,{1,2,1}}, {1,2,3,{1,2,1}} ) ) -- prints true
print( recursive_compare( {1,2,3,{1,2,1}}, {2,2,3,{1,2,3}} ) ) -- prints false