[go-nuts] How to point to pointer struct

[alex martin]

Hi 
I have this structure in C created by rsl libray 

typedef struct {
  Radar_header 
<file:///home/martin/Scaricati/rsl-v1.50/doc/RSL_radar_header_struct.html> h;
  Volume <file:///home/martin/Scaricati/rsl-v1.50/doc/RSL_volume_struct.html> 
**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




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