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RealityV15.1Online Documentation (MoTW) Revision 7

$DEFINE Statement (DataBasic) (m618703+define_s.htm)

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$DEFINE Statement

Declares a symbol for use in a DataBasic program.

Syntax

$DEFINE symbol {value}

Syntax Elements

symbol An identifier to be used as a symbol.

value Any valid DataBasic expression.

Operation

$DEFINE can be used in two ways:

To define a symbol to be equivalent to a DataBasic expression. When you compile your program, a pre-processor replaces all occurrences of each symbol with the corresponding value.
When used in this way, $DEFINE is similar to the EQUATE statement, except that value extends to the end of the line.
To define a symbol for use with the $IFDEF and $IFNDEF statements to control conditional compilation. In this case, value can be omitted.

A symbol defined with $DEFINE can be undefined with the $UNDEFINE statement. It can then be defined again with $DEFINE. Note, however, the following restrictions:

Once set, the value of a defined symbol cannot be changed.
An undefined symbol cannot then be used as a variable.

Comments

Refer to the EQUATE statement for more information about defining a symbol to be equivalent to a DataBasic expression.

Examples

$DEFINE PI 3.1416

Declares symbol PI to be equal to 3.1416.

$DEFINE PART.NO ITEM(3)

Equates PART.NO to array element number 3 of ITEM.

$DEFINE TODAY DATE() 'DJ'

Equates symbol TODAY to the current date, formatted as the Julian day (1-365 or 1-366 for a leap year).

$DEFINE DEBUG