Commodore PET User Manual page 99

Here there is a second statement following the IF ... THEN statement. If the con-
dition is satisfied (A is equal to Dl. both B=C and C=C+1 are executed. If the con-
dition is not satisfied (A is not equal to 0) neither of these actions is executed.
Note particularly that C is not incremented. whereas for the statements:
50 IF A=0 THEN B~C
55 C=C+1
C is incremented whether or not the IF condition is satisfied. since it is on a sepa-
rate line from the IF ... THEN statement.
Multiple statements on one line in a program save some memory space.
since there is only one line number to keep track of. In the general case. it is sug-
gested that vou do not make greater use of multiple statements on a line than
necessary. as in the case of performing several actions for a single IF condition.
Compacted programs are difficult to read. edit. and debug (errors in programs are
commonly referred to as "bugs:' therefore the term "debug" means to eliminate
errors) .
PRINT Formats: Une, Continuous, Tabbed
Normally each PRINT statement prints a new line on the display. That is.
a RETURN is forced. so that the next PRINT statement begins printing at the
beginning of the next line. This can be overridden by placing a semicolon (;) at
the end of the PRINT statement. There is an example of this in the display pro-
gram:
C:$="~.J":FOR 1"'1 TO 800:?C$.; :NE~·~T·?"PHEW!"
------Continuous line format (;)
The semicolon in this PRINT statement is what provides continuous line
printing of the character over 20 lines of the display. If the semicolon were not
there. each character would be printed at the beginning of a new line. or vou
would see ail 800 W's printed in a single column at the left of the screen.
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