Lua有序的表迭代

Question

我需要通過它創建的順序遍歷Lua表。我發現這篇文章 -​​ 不過，這並不好像工作：

function __genOrderedIndex(t) 
local orderedIndex = {} 
for key in pairs(t) do 
    table.insert(orderedIndex, key) 
end 
table.sort(orderedIndex) 
return orderedIndex 
end 

function orderedNext(t, state) 
-- Equivalent of the next function, but returns the keys in the alphabetic 
-- order. We use a temporary ordered key table that is stored in the 
-- table being iterated. 

key = nil 
--print("orderedNext: state = "..tostring(state)) 
if state == nil then 
    -- the first time, generate the index 
    t.__orderedIndex = __genOrderedIndex(t) 
    key = t.__orderedIndex[1] 
else 
    -- fetch the next value 
    for i = 1,table.getn(t.__orderedIndex) do 
     if t.__orderedIndex[i] == state then 
      key = t.__orderedIndex[i+1] 
     end 
    end 
end 

if key then 
    return key, t[key] 
end 

-- no more value to return, cleanup 
t.__orderedIndex = nil 
return 
end 

function orderedPairs(t) 
    return orderedNext, t, nil 
end 

下面是使用例子：

t = { 
['a'] = 'xxx', 
['b'] = 'xxx', 
['c'] = 'xxx', 
['d'] = 'xxx', 
['e'] = 'xxx', 
} 


for key, val in orderedPairs(t) do 
    print(key.." : "..val) 
end 

我得到一個錯誤：

attempt to call field 'getn' (a nil value)

問題是什麼？

Answer 1

table.getn自Lua 5.1以來已被刪除，它被替換爲#運算符。

變化table.getn(t.__orderedIndex)變爲#t.__orderedIndex。