EQUATE

EQUATE is used to declare a symbol equivalent to a literal, variable or simple expression.

COMMAND SYNTAX

EQU{ATE} symbol TO expression

SYNTAX ELEMENTS

symbol is the name of the symbol to use. Can be any name that would be valid for a variable.
expression can be a literal, a variable or a simple expression.

NOTES

Sensible use of EQUATEd symbols can make your program easier to maintain, easier to read, and more efficient.

Efficiency can be enhanced because the address of an EQUATEd value is computed during compilation and is substituted for each occurrence of the symbol name. Unlike the address of a variable, which has to be computed for each access during run time, the address of a symbol is always known. This means that the processing overhead involved in accessing a particular value can be significantly reduced. See the example for a more detailed explanation of the other benefits.

Readability can be enhanced by referring to say, QTY rather than INV_LINE(4). You would simply "EQUATE QTY TO INV_LINE(4)" at an early stage in the program. This can also help with maintenance of the program, particularly in situations where record layouts might change. For example, if the quantity field moves to INV_LINE(6), you will only have to change one line in your program.

EXAMPLE

COMMON FLAG
EQUATE NO_CHARGE TO FLAG
EQUATE CR TO CHAR(13), TRUE TO 1, FALSE TO 0
EQUATE PRICE TO INV_LINE(7), TAX TO 0.175
EQUATE DASHES TO "-------"
IF NO_CHARGE = TRUE THEN PRICE = 0
CRT "Tax =":PRICE * TAX:CR:DASHES

jBC