do generic for loops run more than once? for example if you are looping through a model to put all its children into a table and removing them will it keep looping and add those children that you already removed?
This is a simple yes or no question.
✓ ANSWER ACCEPTED
generic for loops run more than once?
2 answers
✓ Accepted answer
No
Generic for loops do not run more than once. Unless they're in the scope of another loop.
Although, there is a differentiation between the pairs function and ipairs function, it does not effect how many times it iterates.
pairs : Will error if comes across a nil index in the table you're iterating through.
ipairs: Will not error if comes across a nil index in the table you'reiterating through.
1 comment
0
thank you
The iterator expression (expression between in and do) is only executed once^1. However, you pass a table, which is passed by reference, so changes to the table during the loop body might cause the iteration's behavior to change.
I found an old reference to the question
What happens when you modify a table while iterating over it?
An answer, quoting some Lua reference manual, was
The behavior of next is undefined if, during the traversal, you assign any value to a non-existent field in the table.
Assigning values to already existing keys is fine.
I think since table.remove adjusts other keys, you might have a problem.
If you want to be safe, just iterate backwards:
for i = #list, 1, -1 do
if math.random(2) == 1 then
table.remove(list, i)
end
end
This discussion is preserved as it was. New answers, comments, and votes are closed.
2 comments
Just so you know, questions that only require a yes or a no answer are not well suited to this site. You can do simple testing on your own, can't you?
^