On Mon, Sep 30, 2019 at 1:01 AM T L <tapir....@gmail.com> wrote: > > https://golang.org/cmd/cgo/#hdr-Passing_pointers > > When passing a pointer to a field in a struct, the Go memory in question is > the memory occupied by the field, not the entire struct. When passing a > pointer to an element in an array or slice, the Go memory in question is the > entire array or the entire backing array of the slice. > > Why do structs and arrays have this difference?
Because it's normal to call a C function with (&a[0], len(a)) to let the C function examine all elements of the array or slice. It's not normal to call a C function with (&s.f) and expect the C function to examine all elements of the struct; if the C function wants to examine all elements of a struct, you would pass &s, not &s.f. But you don't want to pass &a to a C function; with the way C pointers work, you want to pass a pointer to an element, not a pointer to the array or slice. (Admittedly passing a pointer to an array would work anyhow, but passing a pointer to a slice would not.) Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcVGUomQ3vYgoqVg0-5vgXNhRQCej_tFjxmWNMoLtPyqxQ%40mail.gmail.com.
