Compound Datatypes

Detailed Description

Functions
herr_t	H5Tinsert (hid_t parent_id, const char *name, size_t offset, hid_t member_id)
	Adds a new member to a compound datatype.
herr_t	H5Tpack (hid_t type_id)
	Recursively removes padding from within a compound datatype.
size_t	H5Tget_member_offset (hid_t type_id, unsigned membno)
	Retrieves the offset of a field of a compound datatype.
H5T_class_t	H5Tget_member_class (hid_t type_id, unsigned membno)
	Returns datatype class of compound datatype member.
hid_t	H5Tget_member_type (hid_t type_id, unsigned membno)
	Returns the datatype of the specified member.

Function Documentation

H5Tget_member_class()

H5T_class_t H5Tget_member_class	(	hid_t	type_id,
		unsigned	membno
	)

Returns datatype class of compound datatype member.

Parameters

[in]	type_id	Datatype identifier
[in]	membno	Zero-based index of the field or element

Returns

Returns the datatype class, a non-negative value, if successful; otherwise returns a negative value.

Given a compound datatype, dtype_id, H5Tget_member_class() returns the datatype class of the member specified by member_no.

Valid class identifiers, as defined in H5Tpublic.h, are:

typedef enum H5T_class_t {
    H5T_NO_CLASS  = -1, 
    H5T_INTEGER   = 0,  
    H5T_FLOAT     = 1,  
    H5T_TIME      = 2,  
    H5T_STRING    = 3,  
    H5T_BITFIELD  = 4,  
    H5T_OPAQUE    = 5,  
    H5T_COMPOUND  = 6,  
    H5T_REFERENCE = 7,  
    H5T_ENUM      = 8,  
    H5T_VLEN      = 9,  
    H5T_ARRAY     = 10, 
    H5T_COMPLEX   = 11, 
    H5T_NCLASSES 
} H5T_class_t;

Since

1.4.0

H5Tget_member_offset()

size_t H5Tget_member_offset	(	hid_t	type_id,
		unsigned	membno
	)

Retrieves the offset of a field of a compound datatype.

Parameters

[in]	type_id	Datatype identifier
[in]	membno	Zero-based index of the field or element

Returns

Returns the byte offset of the field if successful; otherwise returns 0 (zero).

H5Tget_member_offset() retrieves the byte offset of the beginning of a field within a compound datatype with respect to the beginning of the compound datatype datum.

Note that zero is a valid offset and that this function will fail only if a call to H5Tget_member_class() fails with the same arguments.

Version

1.6.4 member_no parameter type changed to unsigned.

Since

1.0.0

H5Tget_member_type()

hid_t H5Tget_member_type	(	hid_t	type_id,
		unsigned	membno
	)

Returns the datatype of the specified member.

Parameters

[in]	type_id	Datatype identifier
[in]	membno	Zero-based index of the field or element

Returns

Returns the identifier of a copy of the datatype of the field if successful; otherwise returns a negative value.

H5Tget_member_type() returns the datatype of the specified member. The caller should invoke H5Tclose() to release resources associated with the type.

Version

1.6.4 membno parameter type changed to unsigned.

Since

1.0.0

H5Tinsert()

herr_t H5Tinsert	(	hid_t	parent_id,
		const char *	name,
		size_t	offset,
		hid_t	member_id
	)

Adds a new member to a compound datatype.

Parameters

[in]	parent_id	Datatype identifier
[in]	name	Name of the field to insert
[in]	offset	Offset in memory structure of the field to insert
[in]	member_id	Datatype identifier of the field to insert

Returns

Returns a non-negative value if successful; otherwise, returns a negative value.

H5Tinsert() adds another member to the compound datatype, specified type_id.

The new member has a name which must be unique within the compound datatype. The offset argument defines the start of the member in an instance of the compound datatype, and member_id is the datatype identifier of the new member.

Note

Members of a compound datatype do not have to be atomic datatypes; a compound datatype can have a member which is a compound datatype.

Since

1.0.0

H5Tpack()

herr_t H5Tpack

(

hid_t

type_id

)

Recursively removes padding from within a compound datatype.

Parameters

[in]

type_id

Datatype identifier

Returns

Returns a non-negative value if successful; otherwise, returns a negative value.

H5Tpack() recursively removes padding from within a compound datatype to make it more efficient (space-wise) to store that data.

Since

1.0.0