Thank you problem solved with your suggestion. var PSlv (**C.Volume) = RPointer.v lenght := int(RPointer.h.nvolumes) sliceV := (*[1 << 30](*C.Volume))(unsafe.Pointer(PSlv))[:lenght:lenght]
the result is []*C.Volume correct, where the pointer is null the slice value is nil Alex On Tuesday, May 23, 2017 at 3:42:26 PM UTC+2, Pablo Rozas Larraondo wrote: > > I'm thinking about the possibility of having something like [][]Volume in > Go. Do you know the size or number of Volumes in your struct? > > There's an example of converting **char into []string that might be useful: > https://stackoverflow.com/questions/36188649/cgo-char-to-slice-string > > > > On Tuesday, May 23, 2017 at 8:39:12 PM UTC+10, alex martin wrote: >> >> Hi >> I have this structure in C created by rsl libray >> >> typedef struct { >> Radar_header h; >> Volume **v; >> } Radar; >> >> >> Using cgo i read the structure with >> >> >> Radar *readRad(char *fname) { >> return RSL_anyformat_to_radar(fname, NULL); >> } >> >> >> and call this function in go >> >> RPointer := C.readRad(C.CString(os.Args[1])) >> >> >> and i see the structure >> >> with fmt.Printf("%T",RPointer) => *main._Ctype_struct___0 >> >> with fmt.Printf("%+v",RPointer) => &{h:{} _:[0 0 0 0] *v:0xe59b60*} >> >> >> The field is a **C.Volume pointer. >> >> The question is: it's possible with Golang list all C.Volume's struct >> pointed ? >> >> >> like this >> >> >> for i := 0; i < int(RPointer.h.nvolumes); i++ { >> >> pv := *RPointer.v[i] >> fmt.Printf("\nVOLUME Sweep %+v\n", *pv.sweep) >> } >> >> >> the exit is type **C.struct___2 does not support indexing >> >> >> I tried with unsafe.Pointer using >> >> >> >> *puint1 := unsafe.Pointer(RPointer.v)* >> >> >> *sizep := unsafe.Sizeof(RPointer.v)fmt.Printf("\npuint [%+v] -> + sizeoff >> [%+v]\n", puint1, unsafe.Pointer(uintptr(puint1)+sizep))* >> >> >> and printf is puint [0xe59b60] -> + sizeoff [0xe59b68] >> >> >> there is a casting like this >> >> >> volume2 := (*C.Volume)(*unsafe.Pointer(uintptr(puint1) + sizep)) >> >> >> Thanks >> >> Alex >> >> >> >> >> -- 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. For more options, visit https://groups.google.com/d/optout.
