4D v13.4

BLOB to real

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4D v13.4
BLOB to real

BLOB to real 


 

BLOB to real ( blob ; realFormat {; offset} ) -> Function result 
Parameter Type   Description
blob  BLOB in BLOB from which to get the Real value
realFormat  Longint in 0=Native real format, 1=Extended real format, 2=Macintosh Double real format, 3=Windows Double real format
offset  Variable in Offset within the BLOB (expressed in bytes)
in New offset after reading
Function result  Real in Real value

The BLOB to real command returns a Real value read from the BLOB blob.

The realFormat parameter fixes the internal format and byte ordering of the Real value to be read. You pass one of the following predefined constants provided by 4D:

Constant Type Value
Extended real format Longint 1
Macintosh double real format Longint 2
Native real format Longint 0
PC double real format Longint 3

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

If you specify the optional offset variable parameter, the Read value is read at the offset (starting from zero) within the BLOB. If you do not specify the optional offset variable parameter, the first 8 or 10 bytes of the BLOB are read.

Note: You should pass an offset value between 0 (zero) and the size of the BLOB minus 8 or 10. If you do not do so, an error -111 is generated.

After the call, the variable is incremented by the number of bytes read. Therefore, you can reuse that same variable with another BLOB reading command to read another value.

Example  

The following example reads 20 Real values from a BLOB, starting at the offset 0x200:

 $vlOffset:=0x200
 For($viLoop;0;19)
    $vrValue:=BLOB to real(vxSomeBlob;PC byte ordering;$vlOffset)
  ` Do something with $vrValue
 End for

 
PROPERTIES 

Product: 4D
Theme: BLOB
Number: 553

 
INDEX

Alphabetical list of commands

 
HISTORY 

Created: 4D v6

 
SEE ALSO 

BLOB to integer
BLOB to longint
BLOB to text
INTEGER TO BLOB
LONGINT TO BLOB
REAL TO BLOB
TEXT TO BLOB

 
TAGS 

Real, Byteswapping***