#在Lua中是什么意思? [英] What does # mean in Lua?

问题描述

在Lua中，我已经看到很多哈希字符'#'被添加到变量的前面.

I have seen the hash character '#' being added to the front of variables a lot in Lua.

它是做什么的?

示例

-- sort AIs in currentlevel
table.sort(level.ais, function(a,b) return a.y < b.y end)
local curAIIndex = 1
local maxAIIndex = #level.ais
for i = 1,#currentLevel+maxAIIndex do
    if level.ais[curAIIndex].y+sprites.monster:getHeight() < currentLevel[i].lowerY then
        table.insert(currentLevel, i, level.ais[curAIIndex])
        curAIIndex = curAIIndex + 1
        if curAIIndex > maxAIIndex then
            break
        end
    end
end

很抱歉，如果已经问过这个问题，我已经在互联网上搜索了很多，但似乎还没有找到答案.预先感谢！

Apologies if this has already been asked, I've searched around on the internet a lot but I haven't seem to have found an answer. Thanks in advance!

推荐答案

即

长度运算符由一元运算符#表示.字符串的长度是其字节数(即，每个字符为一个字节时字符串长度的通常含义).

The length operator is denoted by the unary operator #. The length of a string is its number of bytes (that is, the usual meaning of string length when each character is one byte).

表t的长度定义为任何整数索引n，以使t [n]不为nil，t [n + 1]为nil；此外，如果t [1]为nil，则n可以为零.对于具有从1到给定n的非零值的常规数组，其长度恰好是n(其最后一个值的索引).如果数组具有空洞"(即其他非nil值之间的nil值)，则#t可以是直接在nil值之前的任何索引(即，它可以将任何此类nil值视为结尾)的数组).

The length of a table t is defined to be any integer index n such that t[n] is not nil and t[n+1] is nil; moreover, if t[1] is nil, n can be zero. For a regular array, with non-nil values from 1 to a given n, its length is exactly that n, the index of its last value. If the array has "holes" (that is, nil values between other non-nil values), then #t can be any of the indices that directly precedes a nil value (that is, it may consider any such nil value as the end of the array).

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