Commodore 128D User Manual page 281

INPUT
These forms transfer program execution to the specified line number
if the expression is true. Otherwise, the program resumes with the
program line number immediately following the line containing the IF
statement.
EXAMPLE:
50 IF X > 0 THEN PRINT "OK": ELSE END
This line checks the value of X. If X is greater than 0, the statement
immediately following the keyword THEN (PRINT "OK") is executed
and the ELSE clause is ignored. If X is less than or equal to 0, the
ELSE clause is executed and the statement immediately following
THEN is ignored.
10 IF X = 10 THEN 100
20 PRINT "X DOES NOT EQUAL 10"
■
99 STOP
100 PRINT "X EQUALS 10"
This example evaluates the
value of X. IF X equals 10,
the program control is
transferred to line 100 and
the message "X EQUALS
10" is printed. IF X does
not equal 10, the program
resumes with line 20, the
C128 prints the prompt "X
does not equal 10" and
the program stops.
—Receive a buffered data string or a number from the keyboard and
wait for the user to press RETURN
INPUT ["prompt string";] variable list
The INPUT statement asks for data from the user while the program
is RUNning and places the data into a variable or variables. The pro
gram stops, prints a question mark (?) on the screen, and waits for
the user to type the answer and hit the RETURN key. The word
INPUT is followed by a prompt string and a variable name or list of
variable names separated by commas. The message in the prompt
string inside quotes suggests (prompts) the information the user
should enter. If this message is present, there must be a semicolon
(;) after me closing quote of the prompt.
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BASIC 7.0 ENCYCLOPEDIA—Basic Commands and Statements