UNASSIGNED
Synopsis
UNASSIGNED(var)
Arguments
| var | A user variable. If var is not a valid variable name, MVBasic issues a syntax error. |
Description
The UNASSIGNED function determines whether a variable is assigned or not assigned. If var is not assigned a value, UNASSIGNED returns 1. If var is assigned a value, UNASSIGNED returns 0. An assigned value can be a single value, a dynamic array value, or the null string.
The input var can be a local variable, a global variable, or a process-private global variable. It can be with or without subscripts.
UNASSIGNED should not be used on system variables (@ variables). It always returns 1 for all @ variables, whether or not the @ variable currently has a value.
The COMMON statement initializes variables as unassigned in Caché MVBasic. Array variable initialization varies with different MultiValue emulations. You can use the $KILL statement to unassign user variables.
The ASSIGNED function is the functional opposite of the UNASSIGNED function.
Examples
The following example tests the assignment of several variables. UNASSIGNED returns 0 (assigned) for all of these variables:
a=123
b="fred"
c=1:@VM:2:@VM:3
d=""
^a="fruit"
^a(3)="banana"
^||a="ppv"
PRINT UNASSIGNED(a)
PRINT UNASSIGNED(b)
PRINT UNASSIGNED(c)
PRINT UNASSIGNED(d)
PRINT UNASSIGNED(^a)
PRINT UNASSIGNED(^a(3))
PRINT UNASSIGNED(^||a)
