Sharp PC-1403 Operation Manual page 153

147
This program continues to ask 'CONTINUE?'
as long as 'YES' is entered;
it
stops if
'NO' is entered, and complains otherwise.
10 INPUT "CONTINUE?"; A$
20 IF A$="YES" THEN GOTO 10
30 IF A$="NO" THEN GOTO 60
40 PRINT "YES OR NO, PLEASE"
50
END
Examples
The statement which follows the THEN may be any BASIC statement, including
another IF ... THEN, If it is
a
LET statement, the LET verb itself must appear.
The two formats of the IF statement are identical in action, but the first format is clear.
*
1
#1
In the normal running of BASIC programs, statements are executed in the sequence in
which they occur. The IF ... THEN verb pair allows decisions to be made during
execution so that a given statement is executed only when desi r ed. When the condition
part of the IF statement is true, the statement is executed; when it is false, the
statement is skipped.
The condition part of the IF statement can be any relational expression as described in
Chapter 4. It is also possible to use a numeric expression as a condition, although the
intent of the statement will be less clear. Any expression which evaluates to zero or a
negative number is considered false; any which eval u ates to a positive number is
consi d ered true.
•A!IM·Mi
The IF ... THEN verb pair is used to execute or not to execute a statement depending
on conditions at the time the program is run.
Abbreviations: none for IF; T, TH., THE.
1 IF condition THEN statement
2 JF condition statement
Verbs
IF ... THEN