[Haskell-cafe] converting between a Ptr a and an Integer

[Carter Schonwald]

There is a module in base that let's you do pointer arith in Haskell. I
forget where it is.  But it's there.

No need to cast your pointer to an int and back.

On Saturday, December 7, 2013, Sylvain HENRY wrote:

> Hi,
>
> You can use:
> ptrToIntPtr :: Ptr a -> IntPtr
> intPtrToPtr :: IntPtr -> Ptr a
>
> Cheers
> Sylvain
>
>
> Le 07/12/2013 18:58, keydana at gmx.de a écrit :
>
>> Hi,
>>
>> is there any way to convert between a Ptr a and an Integer?
>> (I would like to attach to shared memory and dereference pointers to
>> certain memory addresses, as you would do in C.)
>>
>> If there is no way at all, I think I could still get along by defining
>> c_shmat as
>>
>> c_shmat :: CInt ->  CInt -> CInt -> IO (Ptr a)
>>
>> and perform calculations using plusPtr,
>>
>> but then how do I check if I got back the correct address, and not (void
>> *) -1, which is what shmat returns on error?
>>
>> Any help very much appreciated!
>>
>> Thanks
>> Sigrid
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>
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