how to initialize an array of typedef-ed type?

The fact that D has real typedef, not like the fake ones of C++ is, I think, one of its great features. But the fact that there is no automatic cast, together with typedef is causing me problems. The one I'm currently fighting with is initialization: typedef long location ; location a[] = [1,2,3,4] ; // doesn't work: Error: cannot implicitly convert expression (btw. gdc has no problem, only dmd) is there any nice way to do that? Using [1L,2L,3L,4L] is uglier, and still doesn't work. The only thing that works is location a[] = [cast(location)(1), cast(location)(2), cast(location)(3), cast(location)(4)]; which is SOMEWHAT ugly. So, given that typedef is one of the great features of D, are you using it? How? Or are you usually using alias? Thanks!

typedef long location ; location a[] = cast(location[])[1,2,3,4] ; Seems to work. I was afraid of the mess that would happen if I cast (int *) to (long *) in C... Can I trust it? Is that the "right way" to do it? MLT Wrote: > The fact that D has real typedef, not like the fake ones of C++ is, I think, one of its great features. > > But the fact that there is no automatic cast, together with typedef is causing me problems. > > The one I'm currently fighting with is initialization: > > typedef long location ; > > location a[] = [1,2,3,4] ; // doesn't work: Error: cannot implicitly convert expression > > (btw. gdc has no problem, only dmd) > > is there any nice way to do that? Using [1L,2L,3L,4L] is uglier, and still doesn't work. The only thing that works is > location a[] = [cast(location)(1), cast(location)(2), cast(location)(3), cast(location)(4)]; > > which is SOMEWHAT ugly. > > So, given that typedef is one of the great features of D, are you using it? How? Or are you usually using alias? > > Thanks!

On Fri, May 1, 2009 at 9:15 AM, MLT <none@anone.com> wrote: > > typedef long location ; > location a[] = cast(location[])[1,2,3,4] ; > > Seems to work. > I was afraid of the mess that would happen if I cast (int *) to (long *) in C... > Can I trust it? Is that the "right way" to do it? Have you actually run it and seen what the results are? If it works, well, use it :) (It does work, and that is the right way to do it.)

Jarrett Billingsley Wrote: > On Fri, May 1, 2009 at 9:15 AM, MLT <none@anone.com> wrote: > > > > typedef long location ; > > location a[] = cast(location[])[1,2,3,4] ; > > > > Seems to work. > > I was afraid of the mess that would happen if I cast (int *) to (long *) in C... > > Can I trust it? Is that the "right way" to do it? > > Have you actually run it and seen what the results are? If it works, well, use it :) > > (It does work, and that is the right way to do it.) Yes, it does work! At first I thought that maybe on my machine int and long have the same length, or some such. But it works, for int, long, and short. And they do have different lengths. I tried a bit more: --- typedef long tlong ; void main() { int[] x = [1,2,3,4] ; tlong[] y = cast(tlong[])[1,2] ; // <- this works Stdout(y).newline ; y = cast(tlong[]) x ; // This doesn't Stdout(y).newline ; } --- prints out: [1, 2] [8589934593, 17179869187] The the initialization works, but casting from int[] to long[] in general doesn't.

On Fri, May 1, 2009 at 10:07 AM, MLT <none@anone.com> wrote: > At first I thought that maybe on my machine int and long have the same length, or some such. But it works, for int, long, and short. And they do have different lengths. D's integer types are not like C's. They are fixed size and do not vary from platform to platform. See http://www.digitalmars.com/d/1.0/type.html > I tried a bit more: > --- > typedef long tlong ; > > void main() > { > int[] x = [1,2,3,4] ; > > tlong[] y = cast(tlong[])[1,2] ; // <- this works > > Stdout(y).newline ; > > y = cast(tlong[]) x ; // This doesn't > > Stdout(y).newline ; > } > --- > prints out: > [1, 2] > [8589934593, 17179869187] > > The the initialization works, but casting from int[] to long[] in general doesn't. You're actually doing two different things there. Initialization is treated as a special case and casting it will cast each element. But array casts done at runtime will do a bit cast - that is, given your int[] [1, 2, 3, 4], when you cast it to a long[] at runtime, it takes that chunk of memory, figures out how many longs will fit in it (in this case 2), and gives you a new array reference to the same data but with a different type. Those big weird numbers are 0x00000002_00000001 and 0x00000004_00000003, respectively. Woah look at that, 1, 2, 3, 4! To make it more apparent, try casting an int[] to a byte[] or something. You'll see that it then splits up each original int into four bytes.