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- Subject: Re: Integers-related trap in Lua 5.3
- From: "Soni L." <fakedme@...>
- Date: Tue, 17 May 2016 09:55:31 -0300
On 16/05/16 11:57 PM, Sean Conner wrote:
It was thus said that the Great Soni L. once stated:
On 16/05/16 07:09 PM, Sean Conner wrote:
It was thus said that the Great Egor Skriptunoff once stated:
It appears that in Lua 5.3 usual call to tonumber() is not enough
to correctly parse numbers entered by user from file or keyboard.
local googol = tonumber("1"..("0"):rep(100))
gives zero (instead of 1e+100 as in previous Lua versions).
I've read the other messages in this thread, and my question is: why
was the behavior of tonumber() even changed for Lua 5.3? Have it always
return a double because math.tointeger() exists to parse integers. You
want a number, use tonumber(). You want to ensure you parse an integer,
use math.tointeger(). That would at least prevent problems like this
>from happening in the first place.
math.tointeger(9223372036854775807.0) ~= 9223372036854775807 so it can't
just always return a double. But it would be nice if it was smart about it.
You misunderstood me.
tonumber() always returns a double or nil if not a double
math.tointeger() always returns an integer or nil if not an integer
tonumber() isn't smart. math.tointeger() isn't smart.
You mean using strings with math.tointeger()?
If that's the case, I think we should have math.tointeger() and
math.tofloat(), and tonumber() should be smart. For backwards
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