* [Caml-list] OCaml max_int and min_int in C
@ 2016-07-18 8:43 Richard W.M. Jones
2016-07-18 8:59 ` Jeremy Yallop
0 siblings, 1 reply; 3+ messages in thread
From: Richard W.M. Jones @ 2016-07-18 8:43 UTC (permalink / raw)
To: caml-list
This almost feels like an FAQ but I can't find the answer anywhere.
We need to check that an integer being returned from some C bindings
isn't larger or smaller than Pervasives.max_int / min_int. Are there
C macros or constants containing these bounds? Obviously we can
define our own but it seems better to use ones from OCaml if they
exist.
Rich.
--
Richard Jones
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Caml-list] OCaml max_int and min_int in C
2016-07-18 8:43 [Caml-list] OCaml max_int and min_int in C Richard W.M. Jones
@ 2016-07-18 8:59 ` Jeremy Yallop
2016-07-18 9:04 ` Richard W.M. Jones
0 siblings, 1 reply; 3+ messages in thread
From: Jeremy Yallop @ 2016-07-18 8:59 UTC (permalink / raw)
To: Richard W.M. Jones; +Cc: Caml List
On 18 July 2016 at 09:43, Richard W.M. Jones <rich@annexia.org> wrote:
> We need to check that an integer being returned from some C bindings
> isn't larger or smaller than Pervasives.max_int / min_int. Are there
> C macros or constants containing these bounds? Obviously we can
> define our own but it seems better to use ones from OCaml if they
> exist.
There are Max_long and Min_long:
https://github.com/ocaml/ocaml/blob/ebbe205d/byterun/caml/mlvalues.h#L75-L76
Here's an example of Max_long being used to check that the return
value of lseek fits in an OCaml int:
https://github.com/ocaml/ocaml/blob/ebbe205d/otherlibs/unix/lseek.c#L46-L50
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Caml-list] OCaml max_int and min_int in C
2016-07-18 8:59 ` Jeremy Yallop
@ 2016-07-18 9:04 ` Richard W.M. Jones
0 siblings, 0 replies; 3+ messages in thread
From: Richard W.M. Jones @ 2016-07-18 9:04 UTC (permalink / raw)
To: Jeremy Yallop; +Cc: Caml List
On Mon, Jul 18, 2016 at 09:59:40AM +0100, Jeremy Yallop wrote:
> On 18 July 2016 at 09:43, Richard W.M. Jones <rich@annexia.org> wrote:
> > We need to check that an integer being returned from some C bindings
> > isn't larger or smaller than Pervasives.max_int / min_int. Are there
> > C macros or constants containing these bounds? Obviously we can
> > define our own but it seems better to use ones from OCaml if they
> > exist.
>
> There are Max_long and Min_long:
>
> https://github.com/ocaml/ocaml/blob/ebbe205d/byterun/caml/mlvalues.h#L75-L76
>
> Here's an example of Max_long being used to check that the return
> value of lseek fits in an OCaml int:
>
> https://github.com/ocaml/ocaml/blob/ebbe205d/otherlibs/unix/lseek.c#L46-L50
So there is! I was grepping for MAX & INT, not Max and long :-/
Thanks,
Rich.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-07-18 8:43 [Caml-list] OCaml max_int and min_int in C Richard W.M. Jones
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