如何按确切顺序遍历表? [英] How to iterate through a table in its exact order?

问题描述

如果我尝试输出这个表，它们会以错误的顺序循环:

If i try to output this table, they are looped through in the false order:

local letters   =   {DIN1="hi", AIN1= "my", AIN2 ="name", DIN2="is"}

for name, value in pairs(letters) do
    print(name,value)
end

预期输出:

DIN1   hi
AIN1   my
AIN2    name
DIN2   is

输出:

AIN1    my
DIN2    is
DIN1    hi
AIN2    name

我该如何编码以便 for 循环遍历表格的实际顺序?(定义顺序)

How can i code it so that the for loop runs through the tables actual order? (The order how it was defined)

我不需要字母顺序，但与表定义中的顺序相同.

I don't need the alphabetic order, but the same order as in the definition of the table.

我需要打印密钥和值.在答案Lua 成对与编写的顺序相同"中，只会打印索引号和值

I need to have the key AND the value printed. In the answer "Lua in pairs with same order as it's written" there will be only indexnumber and value printed

推荐答案

你可以利用表的整数部分按顺序存储键:

You may utilize integer part of the table to store keys in order:

function add(t, k, v, ...)
    if k ~= nil then
        t[k] = v
        t[#t+1] = k
        return add(t, ...)
    end
    return t
end

t = add({ }, "A", "hi", "B", "my", "C", "name", "D", "is")

for i,k in ipairs(t) do
    local v = t[k]
    print(k, v)
end

当然，这假设除了 add 之外的任何东西都不使用整数键.

Of course, this assumes that integer keys are not used by anything except add.

insert(t, k, v) 和 remove(t, k) 作为练习留给读者.

insert(t, k, v) and remove(t, k) left as an exercise to the reader.

add 函数中的省略号(点)允许根据需要传递尽可能多的参数来一次设置多个 kv 对.没有它，我们每次调用只能设置一对，例如 add(t, "A", "hi").函数定义 add(t, k, v, ...) 将前三个参数分配给 t, k, v 并保留其他参数不变.然后 add 处理第一对 (t[k]=v) 并使用其余的 ... 参数递归.

Ellipsis (dots) in add function allow passing as many arguments as needed to set many kv-pairs at once. Without that, we would be only able to set one pair per call, like add(t, "A", "hi"). Function definition add(t, k, v, ...) assigns first three arguments to t, k, v and leaves others untouched. Then add processes first pair (t[k]=v) and recurses with the rest ... of arguments.

          t   k    v    ...
level 1: (t, "A", "hi", "B", "my", "C", "name", "D", "is")
level 2: (t,         <- "B", "my", "C", "name", "D", "is")
level 3: (t,                    <- "C", "name", "D", "is")
level 4: (t,                                 <- "D", "is")
level 5: (t,                                          <- )

在第 5 级，k 和 v 取 nils，因为参数列表太短，递归停止.

At level 5, k and v take nils, because argument list is too short, and recursion stops.

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