Then; Goto - Sharp PC-1500A Instruction Manual

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Several endings are not the result of good programming practice. Our reversal of these statements
does demonstrate though, that correct ordering of statements and proper testing are necessary fo r
a program to operate correctly. In the next section, we will observe
a
third way to phrase our
program which involves the GOTO statement and solves the problems of the second version.
Although the condition of an IF statement is usually an inequality, it is not necessarily so. In
PC·1500A BASIC any expres.sion which evaluates to non.zero is considered to be True. Any
expres.sion which evaluates to zero is considered to be false. This explains why inequalities work
as conditions: remember that an inequality whichi is True returns a 1 and inequalities that are
False return a 0.
One more reminder is in order. If the statement which folloi.vs the T HEN is an
assign1nent
statement, the LET keyword MUST be used. Failure to do so will cause an ERROR condition to
occur. This was dis.cussed in the section on the LET S1atcment.
Caution : Refer to page 164.
0. GOTO
You may have noticed. in the last section, that our options .. vere limited after the test was made
in the IF statement. We \vere only allowed to execute one statement if the cond ition was True.
For conven ience, w e would like to execute several statements. The
GOTO
statement allO\\IS us to
do this.
The GOTO statement modifies the "flow" of suatcmcnt execution. It tells SHARP to " go to"
a line other than the next one and begin executing statements sequentially from there. The
effect of this "jump" is that some statements may be skipped entirely. For example review the
following program:
Program Listing:
10 PAUSE "ESCHEW ";
20 GOTO
50
30 PRINT X*3/4+2
40 PRINT "A BOOK WHICH EMPLOYS";
50 PR INT "OBFUSCAT ION!"
60 ENO
Keystrokes:
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46
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