libxrdeveloper's documentation
gboolean xr_value_to_double ( xr_value val,
double *  nval 
)

Extract xr_value of type XRV_DOUBLE into the native language type.

Parameters
valValue node. May be NULL, see below.
nvalPointer to the variable where value should be extracted. This pointer must not be NULL.
Returns
This function returns FALSE if value can't be extracted, this may happen when val is NULL or val is not of expected node type. On error value pointed to by nval is not modified. TRUE is returned on success.
Documentation for libxr, Wed Apr 27 2016 22:07:49.