Commodore VIC-20 - Page 41

When this program runs, the question mark appears to prompt
the operator that the VtC is expecting an input for line 100. Any
number typed in goes into A, for later use in the program. If the
answer typed was not a number, the ?REDO FROM START
message appears, which means that a string was received when a
number was expected. If the operator just hit RETURN without
typing anything, the variable's value doesn't change.
Now the next question mark, for line 110, appears. If we type only
one number and hit RETURN, the V!C will now display 2 question
marks (??), which means that more input is required. You can just
type as many inputs as you need separated by commas, which
prevents the double question mark from appearing. If you type
more data than the INPUT statement requested, the ?EXTRA
IGNORED message appears, which means that the extra items
you typed were not put into any variables.
Line 120 displays the word PROMPT before the question mark
appears. The semicolon is required between the prompt and any
list of variables. Note: The only way to end a program during
an INPUT statement is to hold down the RUN/STOP key and
hit RESTORE.
EXAMPLE 2:
10 PRINT "INPUT A WORD":INPUT AS
20 PRINT -YOUR INPUT WAS"AS
30 GOTO 10
LET
Format: Abbreviation: Screen Display:
expression
The LET statement is used to set a variable to a value. The value
can be a constant (like 5) another variable (like C), or a complex
formula (like PPR-3). The LET statement also works with string
variables.
Since the LETstatement is used so often in BASIC programs, the
word 'LET' has been made optional, since it did nothing but take up
memory. Advanced programmers always leave it out.
LET B=1 This is the same as B=1
A = 3'3-33-B A will equal 41
AS = "CAT" - "DOG" AS will equal "CATDOG"
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