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round, i64round

Library: fbudf

Added in: 1.0 (Win), 1.5 (Linux)

Changed in: 1.5, 2.0.6

Description

These functions return the whole number that is nearest to their (scaled numeric/decimal) argument. They do not work with floats or doubles.

Result type: INTEGER / NUMERIC(18,4)

Syntax

 round (number)
 i64round (bignumber)

Caution: Halves are always rounded upward, i.e. away from zero for positive numbers and toward zero for negative numbers. For instance, 3.5 is rounded to 4, but -3.5 is rounded to -3.

Bug alert: In versions 2.0 through 2.0.5, these functions are broken for negative numbers:

• Anything between 0 and -0.6 (that's right: -0.6, not -0.5) is rounded to 0.
• Anything between -0.6 and -1 is rounded to +1 (plus 1).
• Anything between -1 and -1.6 is rounded to -1.
• Anything between -1.6 and -2 is rounded to -2.
• Etcetera.
  

Fixed in 2.0.6 (backport from 2.5).

Declarations

In Firebird 1.0.x, the entry point for both functions is round:

 DECLARE EXTERNAL FUNCTION Round
   INT BY DESCRIPTOR, INT BY DESCRIPTOR
   RETURNS PARAMETER 2
   ENTRY_POINT 'round' MODULE_NAME 'fbudf'

 DECLARE EXTERNAL FUNCTION i64Round
   NUMERIC(18,4) BY DESCRIPTOR, NUMERIC(18,4) BY DESCRIPTOR
   RETURNS PARAMETER 2
   ENTRY_POINT 'round' MODULE_NAME 'fbudf'

In Firebird 1.5, the entry point has been renamed to fbround:

 DECLARE EXTERNAL FUNCTION Round
   INT BY DESCRIPTOR, INT BY DESCRIPTOR
   RETURNS PARAMETER 2
   ENTRY_POINT 'fbround' MODULE_NAME 'fbudf'

 DECLARE EXTERNAL FUNCTION i64Round
   NUMERIC(18,4) BY DESCRIPTOR, NUMERIC(18,4) BY DESCRIPTOR
   RETURNS PARAMETER 2
   ENTRY_POINT 'fbround' MODULE_NAME 'fbudf'

If you move an existing database from Firebird 1.0.x to 1.5 or higher, drop any existing *round and *truncate declarations and declare them anew, using the updated entry point names. From Firebird 2.0 onward you can also perform this update with ALTER EXTERNAL FUNCTION.

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