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13.09.2016 11:53, Marc Balmer пишет:
Program:
Lua
5.3.3 Copyright (C) 1994-2016 Lua.org, PUC-Rio > a={}
>
a[1]=1
>
a[2]=nil
>
a[3]=3
>
a[4]=4
>
print(#a)
4
should
returns value 1 but because a[2] is nil, it should
return value 1 according book “Programming in Lua (Third
edition)” – there is hole in sequence.
No, this is not a bug. The length operator #, when used on
tables, is only defined for sequences.
btw, "Programming Lua, Fourth Edition" is out, you might
consider an "update"... Especially since
the new edition contains a nice explanation in chapter 5.3
which the length operator on tables
with nil's is such a nice source of confusion...
I think this explanation must be in official doc if it's a source
of confusion.
print(# {[1] = 10, [2] = 20, [3] = nil, [4] = nil, [5] = 40} ) -- is
not sequence ?
print(# {10, 20, nil, nil, 40} ) -- is sequence ? From doc: Note
that a table like {10, 20, nil, 40}
is not a sequence...
output:
2
5
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