Firebird 2.1 Language Reference Update

Library: ib_udf
Changed in: 1.0, 2.0
Better alternative: Internal function ASCII_CHAR()
External functions (UDFs)
ascii_char
Description: Returns the ASCII character corresponding to the integer value passed in.
Result type: VARCHAR(1)
Syntax (unchanged):
ascii_char (intval)
Declaration:
Notes:
DECLARE EXTERNAL FUNCTION ascii_char
INTEGER NULL
RETURNS CSTRING(1) FREE_IT
ENTRY_POINT 'IB_UDF_ascii_char' MODULE_NAME 'ib_udf'
The declaration reflects the fact that the UDF as such returns a 1-character C string, not an SQL
CHAR(1) as stated in the InterBase declaration. The engine will pass the result to the caller as a
VARCHAR(1) though.
The NULL after INTEGER is an optional addition that became available in Firebird 2. When declared
with the NULL keyword, the engine will pass a NULL argument unchanged to the function. This causes
a NULL result, which is correct. Without the NULL keyword (your only option in pre-2.0 versions),
NULL is passed to the function as 0 and the result is an empty string.
For more information about passing NULLs to UDFs, see the note at the end of this book.
• ascii_char(0) returns an empty string in all versions, not a character with ASCII value 0.
• Before Firebird 2.0, the result type was CHAR(1).
Library: ib_udf
Added in: IB
Better alternative: Internal function ASCII_VAL()
ascii_val
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