如何获取Lua表中的条目数? [英] How to get number of entries in a Lua table?

问题描述

听起来像是让我为您代劳"，但是我却找不到答案. Lua #运算符仅对带有整数键的条目进行计数，table.getn也是如此:

Sounds like a "let me google it for you" question, but somehow I can't find an answer. The Lua # operator only counts entries with integer keys, and so does table.getn:

tbl = {}
tbl["test"] = 47
tbl[1] = 48
print(#tbl, table.getn(tbl))   -- prints "1     1"

count = 0
for _ in pairs(tbl) do count = count + 1 end
print(count)            -- prints "2"

如何获得 all 个条目的数量而不计数?

How do I get the number of all entries without counting them?

推荐答案

您已经有了问题的解决方法–唯一的方法是使用pairs(..)迭代整个表.

You already have the solution in the question -- the only way is to iterate the whole table with pairs(..).

function tablelength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

此外，请注意，#"运算符的定义要比这复杂得多.让我通过这张表来说明这一点:

Also, notice that the "#" operator's definition is a bit more complicated than that. Let me illustrate that by taking this table:

t = {1,2,3}
t[5] = 1
t[9] = 1

根据手册， 3、5和9中的任何一个对于#t是有效的结果.唯一合理的使用方式是使用一个不包含nil值的连续部分组成的数组.

According to the manual, any of 3, 5 and 9 are valid results for #t. The only sane way to use it is with arrays of one contiguous part without nil values.

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