Field
 
Specifies field alignment.

Syntax

Type|Union typename Field = { 1 | 2 | 4 }
...
End Type|Union

Description

Field can be used to pack Types or Unions more tightly than the default layout. The most commonly used value is Field = 1, which causes the Type or Union to be packed as tightly as possible, without any padding bytes being added between the fields or at the end of the Type. Field can only be used to decrease field alignment, but it cannot be used to increase it. In order to add padding bytes, a Union with appropriate members could be used instead.

Example

Type bitmap_header Field = 1
    bfType          As UShort
    bfsize          As ULong
    bfReserved1     As UShort
    bfReserved2     As UShort
    bfOffBits       As ULong
    biSize          As ULong
    biWidth         As ULong
    biHeight        As ULong
    biPlanes        As UShort
    biBitCount      As UShort
    biCompression   As ULong
    biSizeImage     As ULong
    biXPelsPerMeter As ULong
    biYPelsPerMeter As ULong
    biClrUsed       As ULong
    biClrImportant  As ULong
End Type

Dim bmp_header As bitmap_header

'Open up bmp.bmp and get its header data:
'Note: Will not work without a bmp.bmp to load . . .
Open "bmp.bmp" For Binary As #1

    Get #1, , bmp_header
    
Close #1

Print bmp_header.biWidth, bmp_header.biHeight

Sleep



Dialect Differences

  • In the -lang qb dialect, the compiler assumes Field = 1 by default, if no other Field was specified, causing all structures to be tightly packed, without added padding, as in QB.

Differences from QB

  • In QB Field was used to define fields in a file buffer at run time. This feature is not implemented in FB, so the keyword has been redefined. To define fields in a file buffer, Types must be used.

See also