[swift-users] Mapping C semantics to Swift

[Ramakrishna Mallireddy]

An working example,

let fm = NSFileManager.defaultManager()

  var mh = mach_header()   // Defined as C struct, <mach-o/loader.h>

  var lc = load_command()  // Defined as C struct <mach-o/loader.h>

  var location = 0

  if let data = fm.contentsAtPath("home/user/projects/some.o") {

    data.getBytes(&mh, length: sizeof(mach_header))

    location += sizeof(mach_header)

    data.getBytes(&lc, range: NSRange(location: location, length: sizeof(
load_command)) )

    location += sizeof(load_command)

}

-Rk

On Thu, May 19, 2016 at 10:52 PM, Joe Groff via swift-users <
swift-users at swift.org> wrote:

>
> > On May 19, 2016, at 10:00 AM, Ken Burgett via swift-users <
> swift-users at swift.org> wrote:
> >
> > I would like to know if a struct in Swift has any guarantee of
> contiguity, like a struct in C.  I am attempting to port a C program that
> makes many assumptions about the underlying semantics of C structs, and
> does things like overlaying an array over the struct using a cast, and then
> performs and cryptographic hashing of the entire struct by treating it as
> an array.
> >
> > 1.  I a Swift struct contiguous?
> >
> > 2.  If 1 above is true, can I somehow cast an array over the struct?
>
> Swift structs have unspecified layout. If you depend on a specific layout,
> you should define the struct in C and import it into Swift for now.
>
> -Joe
> _______________________________________________
> swift-users mailing list
> swift-users at swift.org
> https://lists.swift.org/mailman/listinfo/swift-users
>
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