Casting byte[] to int/long

[Gregor Richards]

Bill Baxter wrote:
> Henrik wrote:
> 
>> Hello!
>>
>> If I have a dynamic array of bytes, say
>>
>> byte[] a; a = [1,2,3,4];
>>
>> Is it possible to somehow cast a number of these bytes into an int or 
>> a long,
>> like so;
>>
>> int b = cast(int)a[0..2];
>> long c = cast(long)a;
>>
>> or something? The goal is to convert 2 * 8 bit into 1 * 16 bit or 4 * 
>> 8 bit
>> into 1 * 64 bit. 1) Is it possible? 2) Is it possible without 
>> confusing the
>> GC? 3) How? ;)
> 
> 
> You need something like:
>   int b = *cast(int*)&a[0];
>   long c = *cast(long*)a.ptr;
> 
> --bb

You probably know this, but be very careful while doing this, endianness 
makes all the difference:

int main()
{
     long a = 10;
     int *b = cast(int *) &a;
     writefln("%d", *b);
}

(Untested) That code will print 10 on a little-endian system, but will 
print 0 on a big-endian system.

  - Gregor Richards