4D Doc Center : LONGINT TO BLOB

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4D v14.3

BLOB

LONGINT TO BLOB


LONGINT TO BLOB ( longInt ; blob ; byteOrder {; offset \| *} )

Parameter	Type	Description
longInt	Longint	Long Integer value to write into the BLOB
blob	BLOB	BLOB to receive the Long Integer value
byteOrder	Longint	0 Native byte ordering 1 Macintosh byte ordering 2 PC byte ordering
offset \| *	Variable, Operator	Offset within the BLOB (expressed in bytes) or * to append the value
		New offset after writing if not *

Description

The LONGINT TO BLOB command writes the 4-byte Long Integer value integer into the BLOB blob.

The byteOrder parameter fixes the byte ordering of the 4-byte Long Integer value to be written. You pass one of the following predefined constants provided by 4D:

Constant	Type	Value
Macintosh byte ordering	Longint	1
Native byte ordering	Longint	0
PC byte ordering	Longint	2

Note regarding Platform Independence: If you exchange BLOBs between Macintosh and PC platforms, it is up to you to manage byte swapping issues while using this command.

If you specify the * optional parameter, the 4-byte Long Integer value is appended to the BLOB and the size of the BLOB is extended accordingly. Using the * optional parameter, you can sequentially store any number of Integer, Long Integer, Real or Text values (see other BLOB commands) in a BLOB, as long as the BLOB fits into memory.

If you do not specify the * optional parameter nor the offset variable parameter, the 4-byte Long Integer value is stored at the beginning of the BLOB, overriding its previous contents; the size of the BLOB is adjusted accordingly.

If you pass the offset variable parameter, the 4-byte Long Integer value is written at the offset (starting from zero) within the BLOB. No matter where you write the 4-byte Long Integer value, the size of the BLOB is increased according to the location you passed (plus up to 4 bytes, if necessary). New allocated bytes, other than the ones you are writing, are initialized to zero.

After the call, the offset variable parameter is returned, incremented by the number of bytes that have been written. Therefore, you can reuse that same variable with another BLOB writing command to write another value.

Example 1

After executing this code:

LONGINT TO BLOB(0x01020304;vxBlob;Native byte ordering)

The size of vxBlob is 4 bytes
On PowerPC platform: vxBLOB{0}=$01, vxBLOB{1}=$02, vxBLOB{2}=$03, vxBLOB{3}=$04
On Intel platform: vxBLOB{0}=$04, vxBLOB{1}=$03, vxBLOB{2}=$02, vxBLOB{3}=$01

Example 2

After executing this code:

LONGINT TO BLOB(0x01020304;vxBlob;Macintosh byte ordering)

The size of vxBlob is 4 bytes
On all platforms vxBLOB{0}=$01, vxBLOB{1}=$02, vxBLOB{2}=$03, vxBLOB{3}=$04

Example 3

After executing this code:

LONGINT TO BLOB(0x01020304;vxBlob;PC byte ordering)

The size of vxBlob is 4 bytes
On all platforms vxBLOB{0}=$04, vxBLOB{1}=$03, vxBLOB{2}=$02, vxBLOB{3}=$01

Example 4

After executing this code:

 SET BLOB SIZE(vxBlob;100)

 LONGINT TO BLOB(0x01020304;vxBlob;PC byte ordering;*)

The size of vxBlob is 104 bytes
On all platforms vxBLOB{100}=$04, vxBLOB{101}=$03, vxBLOB{102}=$02, vxBLOB{103}=$01
The other bytes of the BLOB are left unchanged

Example 5

After executing this code:

 SET BLOB SIZE(vxBlob;100)

 vlOffset:=50

 LONGINT TO BLOB(0x01020304;vxBlob;Macintosh byte ordering;vlOffset)

The size of vxBlob is 100 bytes
On all platforms vxBLOB{50}=$01, vxBLOB{51}=$02, vxBLOB{52}=$03, vxBLOB{53}=$04
The other bytes of the BLOB are left unchanged
The variable vlOffset has been incremented by 4 (and is now equal to 54)