For - Sharp PC-1500A Instruction Manual

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comparison of the methods used to begin a program, see the Chapter entitled Beginning Program
Execution). Unlike the RUN command lhe GOTO command will not clear values from any
variables before it begins execution of lhe program.
To begin program exerution with the GOTO command ENTE R:
GOTO line·numbcr
where:
line·numbcr is the number of the first line ol the program to be executed.
NOTE: Specifying a line.number which does not exist will result in an ERROR 1 1.
P. FOR and NEXT
As we saw in the previous section, the abili ty to repeat a series of instructions is very useful. In
fact this feature is so ohen used that BASIC incorporates several staterllents to automate the
process. These are the FOR statement and its partner, the NEXT statement. Together, the FOR
and the NEXT statements enclose a series of instructions which are repeated a number ol times.
The FOR statement has an associated counter variable and a built·in test condition. It also allows
the specification of the initial value and the increment value of the counter variable.
The form for all of this information is:
FOR counter·variablc
~
initial.value TO linal·value STEP increment·value
where:
counter-variable is the name of the variable used to hold the
~oop
count.
initlal·value is the value sto: r ed in the counter·variablc before the lir$t t ime through the loop.
The allowable range for this value is
- 32768
through
32767.
final·value is the number which is used in tho test. If the counter-variable contains a va lue
greater than final·value, the looping is ended. The legal range for this number is
- 32768
through
32767.
STEP increment-value is an optional clause. The increment·value indicates by how much to
increase or decrease the counter·variable each time t hrough the loop. This must be an
integer in the range - 32768 through 32767. II the entire clause is omitted, then
the increment-value is assumed to be one:.
This is a lo t to handle, so let's observe the behavior of some simple, sample programs. The first
program is similar to the version of the CHUG CHUG program which used a counter. Instead of
"chugging" we print the value of the countcr-varlablu C:
15 FOR C
=
1 TO 10
30 PAUSE C
50 NEXT C
(To make this program "CHUG" as before, simply insert statements 10, 20, and 30 from that
program). Notice that this version i$ neater and more concise using fe\'1er statements to accom·
plish the same counting and looping functions than the older version.
In case there is still some •esidual confusion about what the FOR and NEXT statements are
doing,
we
present a oon1parison of a FOR ... NEXT loop with the oquivalent statements:
5 1
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