Apple II User Manual

                In this example, if X is less than 0, the               26 IF X<0 THEN PRINT

                PRINT statement will be executed and                    "ERROR, X NEGATIVE":

                then the GOTO statement will branch to                  GOTO 350

                line 350.  If the X was 0 or positive,

                BASIC will proceed to execute the lines

                after line 26.

STATEMENT       SYNTAX/FUNCTION                                         EXAMPLE

LET             [LET] variable = expression                             300 LET W=X

                Assigns a value to a variable,

                "LET" is optional.                                      310 V=5.1

STATEMENT       SYNTAX/FUNCTION                                         EXAMPLE

NEXT            NEXT [variable] [,variable] ...                         340 NEXT V

                Marks the end of a FOR loop.

                If no variable is given, matches the most               345 NEXT

                recent FOR loop,

                A single NEXT may be used to match                      350 NEXT V,W

                multiple FOR statements.  Equivalent

                to NEXT V:NEXT W.

STATEMENT       SYNTAX/FUNCTION                                         EXAMPLE

ON...GOSUB      ON expression GOSUB line [,line] ...                    110 ON I GOSUB 50,60

                Identical to "ON...GOTO," except that

                a subroutine call (GOSUB) is executed

                instead of a GOTO.  RETURN from the

                GOSUB branches to the statement after

                the ON...GOSUB.

STATEMENT       SYNTAX/FUNCTION                                         EXAMPLE

ON...GOTO       ON expression GOTO line [, line] ...                    100 ON I GOTO 10,20,

                Branches to the line indicated by the                   30,40

                I'th number after the GOTO.  That is:

                IF I=1, THEN GOTO LINE 10

                IF I=2, THEN GOTO LINE 20

                IF I=3, THEN GOTO LINE 30

                IF I=4, THEN GOTO LINE 40.

                If I=0, or I attempts to select a nonexistent

                line (>=5 in this case), the statement after

                the ON statement is executed.  However, if

                I is >255 or <0, an FC error message will

                result.  As many line numbers as will fit on

                a line can follow an ON...GOTO.

                This statement will branch to line 40 if the            105 ON SGN(X)+2

                expression X is less than zero, to line 50 if           GOTO 40,50,60

                it equals zero, and to line 60 if it is greater

                than zero.

STATEMENT       SYNTAX/FUNCTION                                         EXAMPLE

REM             REM any text                                            500 REM NOW SET

                Allows the programmer to put comments                   V=0

                in his program.  REM statements are not

                executed, but can be branched to.  A REM

                statement is terminated by end of line, but

                not by a ":".

                In this case the V=0 will never be executed             505 REM SET V=0:

                by BASIC.                                               V=0