Re: lua_number2int

[David Given <dg@...>]

Brian Weed wrote:
> Today, we converted a project from Lua v5.02 to v5.1.1, and we started
> having a problem when converting double to int.
> I have narrowed my problem down to code that has nothing to do with
> Lua.  But I still wanted to get other people's opinions about it.
> 
> double d = 0xFFFFFFFF;
> int n;
> n = (int)d;
> 
> // n now contains 0x80000000

On my system (Ubuntu Edgy Linux, gcc 4.1.2) n now containts 0x7FFFFFFF, which
is what I would consider to be correct.

> n = (int)(unsigned int)d;
> 
> // n now contains 0xFFFFFFFF

I get this too. I also consider this to be correct, because casting d to an
unsigned int will fit, and will therefore not truncate the value; and casting
an unsigned int to an int doesn't truncate (which I've never really understood).

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