如何在 Lua 中获取哈希表中的键数? [英] How do I get the number of keys in a hash table in Lua?

问题描述

myTable = {}
myTable["foo"] = 12
myTable["bar"] = "blah"
print(#myTable) -- this prints 0

我真的必须遍历表中的项目才能获得键的数量吗?

Do I actually have to iterate through the items in the table to get the number of keys?

numItems = 0
for k,v in pairs(myTable) do
    numItems = numItems + 1
end
print(numItems) -- this prints 2

推荐答案

我尝试了 # 运算符和 table.getn().我认为 table.getn() 会做你想做的事，但事实证明它返回与 # 相同的值，即 0.似乎字典根据需要插入 nil 占位符.

I experimented with both the # operator and table.getn(). I thought table.getn() would do what you wanted but as it turns out it's returning the same value as #, namely 0. It appears that dictionaries insert nil placeholders as necessary.

遍历键并计算它们似乎是获得字典大小的唯一方法.

Looping over the keys and counting them seems like the only way to get the dictionary size.

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