Offsetof

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OffsetOf

Returns the offset of a field within a type.

Syntax

#define OffsetOf(typename, fieldname) CInt( @Cast( typename Ptr, 0 )->fieldname )

Parameters

• typename
• fieldname

Description

For a non-derived type, OffsetOf will return the location fieldname as offset in bytes from the beginning of typename.

For a derived type, OffsetOf will return the location fieldname as offset in bytes from the beginning of its highest base type.
Note: if a member of the base type is overridden by a new member, the offset of the old member cannot be accessed from the derived type.

Remarks

Usage

result = OffsetOf( typename, fieldname )

Dialect Differences

• Not available in the -lang qb dialect unless referenced with the alias __Offsetof.

Differences from QB

• New to FreeBASIC

See also

• Type...End Type
• SizeOf

Examples

Type MyType

  x As Single

  y As Single

  Union

    b As Byte

    i As Integer

  End Union

End Type

Print "OffsetOf x = "; OffsetOf(MyType, x)

Print "OffsetOf y = "; OffsetOf(MyType, y)

Print "OffsetOf b = "; OffsetOf(MyType, b)

Print "OffsetOf i = "; OffsetOf(MyType, i)

Output

OffsetOf x =  0
OffsetOf y =  4
OffsetOf b =  8
OffsetOf i =  8

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Category: Miscellaneous Keywords
Kind: keyword

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.