UniBasic Commands Reference - Rocket Software

ISNV
Syntax
ISNV(expr)
Description
The UniBasic ISNV function tests an expression for the null value. If expr is the null
value, this function returns a code of 1. If the expression is not null, or if it contains
a null value as well as other characters, this function returns a code of 0.
Note: The udtconfig parameter NULL_FLAG must be on for a program that contains
ISNV to compile. With this flag on, the null value represents an unknown value (represented
by @NULL in UniBasic programs), as opposed to an empty string
(represented as “”). IBM recommends that you use @ variables to represent UniData
delimiters and the null value because the ASCII value used to represent these
characters can vary with language group.
Examples
The following program example demonstrates testing for the null value in a variable:
1-403 UniBasic Commands Reference
A=@NULL
IF ISNV(A) THEN PRINT "A is the null value."
This program results in the following output:
A is the null value.
The following program uses the function ISNV to determine if a string consists of the
null value:
PRINT "1.a ISNV(@NULL) = ":ISNV(@NULL)
PRINT "2.a NOT(ISNV(@NULL)) = ":NOT(ISNV(@NULL))
A = "abc":@NULL:"def"
PRINT "1.b ISNV('abc':@NULL:'def') = ":ISNV(A)
PRINT "2.b NOT(ISNV('abc':@NULL:'def')) = ":NOT(ISNV(A))