postgresql pgrouting define C function function with int* arguments

Question

I want to create a psql-C function with an undefined length list of integers (GIDs for example).

An erratic example using V0 function definition that works is like:

int mytest4(int *x, int i){
  int *a  = &(x[6]);
  int j;
  for (j = 0; j < i; j++)
     printf("Passed on %d", a[j]); // sent to logfile
  return a[i];
}

My question concerns the V1 functions to read an int array. I don't understand how to do

PG_FUNCTION_INFO_V1(mytest5);
Datum mytest5(PG_FUNCTION_ARGS){
int *x = PG_GETARG_???(0);
int i = PG_GETARG_INT32(1);
...

Does anyone know how to write the same function, please??

Answer 1

Okay that was a tricky one, you just have to force cast using

int *x = (int *) PG_GETARG_POINTER(1);

and that should do the job...

I still don't get everything, but /usr/include/postgresql/9.1/server/utils/array.h says :

• A standard varlena array has the following internal structure:
  • - standard varlena header word
  • - number of dimensions of the array
  • - offset to stored data, or 0 if no nulls bitmap
  • - element type OID
  • - length of each array axis (C array of int)
  • - lower boundary of each dimension (C array of int)
  • - bitmap showing locations of nulls (OPTIONAL)
  • - whatever is the stored data