(Conversion) judgment on whether Lua table is null

This is often the case in the project script Lua,

1. Local A = {}

2. process

3. Determine whether Table A is empty.

To determine whether a is a null table, I found some code to do this:

If a =={} then

The result is that a ={} always returns false, which is a logical error. The memory address of table A and an anonymous table is compared here.

Some codes do the following:

If table. maxn (A) = 0 then

It is not safe to do so unless the table key is a number and there is no hash part.

Do you really need to traverse the table and find that there is something, and return false jumps out to determine whether it is empty? At least the code is too ugly.

I searched the internet and found that the answer was already provided in the original official manual, that is, the next function built in Lua.

That is, if next (A) = nil then

Next is actually a function used by pairs to retrieve the next content when traversing the table.

It is best to encapsulate the module in the project so that the module does not have the next function locally.

Therefore, the function to determine whether the Lua table is empty after encapsulation is as follows:

Function table_is_empty (t)

Return _ g. Next (t) = Nil

End

Original address http://yy1983228.blog.163.com/blog/static/54211491200881092239485/

(Conversion) judgment on whether Lua table is null