IS NULL

The IS NULL operator checks for NULL values.

Syntax

expr IS [NOT] NULL
  1. expr can be any expression supported by the language.
  2. The NOT keyword negates the comparison.

Usage

The IS NULL operator can be used to test whether the left-hand expression is null, while IS NOT NULL operator can be used to test for non-null values.

This operator applies to most data types, except complex types like BYTE and TEXT.

Example

MAIN
  DEFINE n INTEGER
  LET n = NULL
  IF n IS NULL THEN
     DISPLAY "The variable is NULL."
  END IF
END MAIN