H5I_SEARCH searches through a given ID type to find an object that satisfies the criteria defined by
func. If such an object is found, the pointer to the memory containing this object is returned. Otherwise,
NULL is returned. To do this,
func is called on every member of
type. The first member to satisfy
func is returned.
type parameter is the identifier for the ID type which is to be searched. This identifier must have been created by a call to H5I_REGISTER_TYPE.
func is a function pointer to a function which takes three parameters. The first parameter is a void * and will be a pointer to the object to be tested. This is the same object that was placed in storage using H5I_REGISTER. The second parameter is a hid_t and is the ID of the object to be tested. The last parameter is a void *. This is the
key parameter and can be used however the user finds helpful, or it can be ignored if it is not needed.
func returns 0 if the object it is testing does not pass its criteria. A non-zero value should be returned if the object does pass its criteria.
H5I_search__func_t is defined in H5Ipublic.h and is shown below.
typedef int (*H5I_search_func_t)(void *obj, hid_t id, void *key);
key parameter will be passed to the search function as a parameter. It can be used to further define the search at run-time.
Programming Note for C++ Developers Using C Functions:
If a C routine that takes a function pointer as an argument is called from within C++ code, the C routine should be returned from normally.
Examples of this kind of routine include callbacks such as H5P_SET_ELINK_CB and H5P_SET_TYPE_CONV_CB and functions such as H5T_CONVERT and H5E_WALK2.
Exiting the routine in its normal fashion allows the HDF5 C library to clean up its work properly. In other words, if the C++ application jumps out of the routine back to the C++ “catch” statement, the library is not given the opportunity to close any temporary data structures that were set up when the routine was called. The C++ application should save some state as the routine is started so that any problem that occurs might be diagnosed.