SDDS_table: Address of the SDDS_TABLE structure for the data set.
parameter_index: The integer index of the parameter in the data set. Returned by
SDDS_DefineParameter or obtained from SDDS_GetParameterIndex.
memory: Pointer to memory in which to place the value of the parameter. If NULL,
memory is allocated.
return value: On success, returns a pointer to the location in which the data has been placed. The pointer should
be cast to data-type*, where data-type is the data type of the parameter. Note that
for type SDDS_STRING, data-type is char *. This data is newly-allocated, and may
be modified as needed by the caller. On failure, returns NULL and records an error
message.