错误：尝试索引字段 '?' （零值）

Question

我的 Lua 代码出现以下错误：

尝试索引字段 '?' （零值）

它发生在下面的粗体行上。我该如何解决？

function SendMessageToAdmins(color1, color2, color3, msg)
    for i = 0, maxSlots - 1 do
        if Account[i] and Account[i].Admin >= 1 or Account[i] and Account[i].GameMaster >= 1 then
            SendPlayerMessage(i, color1, color2, color3, string.format("%s", msg))
        end
    end
end

Answer 1

此错误通常来自尝试在非表或 nil 的内容上索引字段。很可能无论Account[i]发生错误时处于什么位置，都不是表或用户数据，而是像字符串或数字这样的内置类型。

Account[i]当您收到该错误时，我首先检查其中的任何类型，然后从那里开始。

查看此错误（我知道的）的两种最常见方法如下：

local t = { [1] = {a = 1, b = 2}, [2] = {c = 3, d = 4} }
-- t[5] is nil, so this ends up looking like nil.a which is invalid
-- this doesn't look like your case, since you check for 
-- truthiness in Account[i]
print(t[5].a)

您可能遇到的情况很可能是这样的：

local t =
{
    [1] = {a = 1, b = 2},
    [2] = 15, -- oops! this shouldn't be here!
    [3] = {a = 3, b = 4},
}
-- here you expect all the tables in t to be in a consistent format.
-- trying to reference field a on an int doesn't make sense.
print(t[2].a)