User`s manual

4-16

100 IF 0<=X AND X<=90 THEN Y=X+180

If both expressions are True then Y will be assigned the value X+180.

Otherwise, control will pass directly to the next program line, skipping the

THEN clause.

NOTE:

THEN is optional in the above and similar statements. However,

THEN is sometimes required to eliminate an ambiguity.

For example,

400 IF Y=M THEN M=O

won't work without THEN.

500 INPUT A$: IF A$="YES" THEN 100

600 INPUT A$: IF A$="YES" GOTO 100

The two statements have the same effect.

THEN

is not optional in line 500

and other

expression

THEN

line number

statements.

100 IF A>0 AND B>0 PRINT "BOTH POSITIVE"

The test expression may be composed of several relational expressions joined

by logical operators AND and OR.

See

THEN, ELSE.

THEN

statement or line number

Initiates the "action clause" of an IF-THEN type statement. THEN

is optional except when it is required to eliminate an ambiguity,

as in

IF A<0 THEN 100

. THEN should also be used in

IF-THEN-ELSE statements.