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- Subject: Re: lua_number2int
- From: askok@...
- Date: Tue, 14 Nov 2006 14:21:00 +0200
There may be several abnormal things regarding the normal
Lua integer handling.
What I find most weird (met in making the "integer
patches") is that floating point values are silently
converted into integers by 'lua_tointeger()'. I would
consider this a BUG, since if a C routine specifically
requests an integer I think it should be provided one.
Anyways, that behaviour remains in the "integer patch" so
that outside behaviour remains unaltered.
Could we have this changed, in say 5.2?
Also "lua_tounsigned()" would be handy.
On Mon, 13 Nov 2006 21:52:56 -0500
"Brian Weed" <email@example.com> wrote:
Today, we converted a project from Lua v5.02 to v5.1.1,
and we started having a problem when converting double to
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;
n = (int)d;
// n now contains 0x80000000
n = (int)(unsigned int)d;
// n now contains 0xFFFFFFFF
(this happens on both VS2005, and GCC 4.0.1 (Apple
Computer, Inc. build 5363))
Since lua_number2int and lua_number2integer both
basically do this: "n = (int)d;"
Wouldn't it be safer to do this: "n = (int)(unsigned
int)d;" so as to preserve the values that would otherwise
be truncated ?
What sort of problems would this cause? Is my fix
The initial problem we got stems from doing this in Lua:
d = 0xFFFFFFFF
// Assuming Foo() is something like this...
int bind_Foo(lua_State *L)
Foo(lua_tointeger(L, 1)); // value passed to Foo()
truncated to 0x80000000