Re: Sort problem
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- Subject: Re: Sort problem
- From: William Roper <lacutis@...>
- Date: 2004年7月26日 11:25:40 -0700
not (a < b) means that if they are equal, it will return true and lua
needs it to be false if they are equal.
where (a > b) returns false if they are equal.
Thats the only case where they are different.
Example:
a b > !<
1 1 F T
1 2 T T
2 1 F F
Very interesting interaction that I'm glad I know now :)
Ryan.
On 2004年7月26日 12:27:23 -0500, Virgil Smith <virgil@nomadics.com> wrote:
> Quick comment/curiosity...
>
> does "return (a > b)" work?
>
> This is different from "return not (a < b)".
>
>
>
> -----Original Message-----
> From: lua-bounces@bazar2.conectiva.com.br
> [mailto:lua-bounces@bazar2.conectiva.com.br]On Behalf Of Michel Machado
> Sent: Monday, July 26, 2004 11:21 AM
> To: lua@bazar2.conectiva.com.br
> Subject: Sort problem
>
> Dears,
>
> The code below (test.lua) fails:
>
> t = {"a", "b", "a", "a"}
>
> table.sort(t,
> function (a, b)
> assert(a ~= nil, "left var is nil!")
> assert(b ~= nil, "right var is nil!")
> return not (a < b) -- I want an inverted sort!
> end)
>
> for i, v in ipairs(t) do
> print(i, v)
> end
>
> The error:
>
> [michel@michel michel]$ lua test.lua
> lua: test.lua:5: left var is nil!
> stack traceback:
> [C]: in function `assert'
> test.lua:5: in function <test.lua:4>
> [C]: in function `sort'
> test.lua:3: in main chunk
> [C]: ?
>
> Did I make some mistake?
>
> [ ]'s
> Michel Machado
>
>