Re: MSVC compilation problem: std::abs<int64_t> does not exist

[Abdelrazak Younes]

On 30/10/2008 18:21, John W. Eaton wrote:
> On 30-Oct-2008, Abdelrazak Younes wrote:
>
> | On 30/10/2008 16:04, Michael Goffioul wrote:
> |>  As the subject says, there's no specialization of abs for int64_t type
> |>  in MSVC. Any idea on how to fix this?
> |>  (Problem occurs in oct-inttypes.h, line 697).
> |
> | template<typename T>  T abs(T t) { return t>  0 ? t : -t; }
>
> That's buggy on my system.
>
> For example, try the following program:
>
>    #include<iostream>
>    #include<climits>
>
>    template<typename T>
>    T
>    abs (T t)
>    {
>      return t>  0 ? t : -t;
>    }
>
>    int
>    main (void)
>    {
>      std::cout<<  LLONG_MAX<<  std::endl;
>      std::cout<<  LLONG_MIN<<  ", "<<  abs (LLONG_MIN)<<  std::endl;
>      std::cout<<  LLONG_MIN+1<<  ", "<<  abs (LLONG_MIN+1)<<  std::endl;
>    

I indeed get this with MSVC2008 on Windows vista:

9223372036854775807
-9223372036854775808, -9223372036854775808
-9223372036854775807, 9223372036854775807

But looking at the definition of those macro, this is not too surprising:

#define LONG_MIN    (-2147483647L - 1) /* minimum (signed) long value */
#define LONG_MAX      2147483647L   /* maximum (signed) long value */

I guess LONG_MIN is meant for comparison not really for being used as a 
value. But I am far from an expert...

Abdel.