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Reality V15.0 ()

NULL Statement (DataBasic) (m618703+null_s.htm)

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NULL Statement

Specifies no operation.

Syntax

NULL

Comment

A NULL statement can be used anywhere in a program where a DataBasic statement is required.

Examples

10 NULL

Results in no operation; however, because it has a statement label, it can be used as an entry point for a GOTO or GOSUB statement. A REM statement would work just as well in this case. The following examples demonstrate more practical uses of the NULL statement.

IF A=0 THEN NULL ELSE
PRINT "A NONZERO"
GOSUB 45
STOP
END

Executes the statements in the ELSE clause if the value of A is nonzero. If A=0, no action is taken and control passes to the statement following END.

READ A FROM "ABC" ELSE NULL

Reads file item ABC and assigns it to variable A. If ABC does not exist, no action is taken.

IF X1 MATCHES "9N" THEN NULL ELSE GOTO 100

Branches to statement 100 if the current value of X1 does not contain 9 numeric characters. If it does, then no action is taken and control passes to the next sequential statement.