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INPUT
Abbreviation:
TYPE: Statement
FORMAT: INPUT [ "<prompt>" ; ] <variable list>
Action: This is a statement that lets the person RUNning the
program "feed" information into the computer. When executed,
this statement PRINTs a question mark (?) on the screen, and positions
the cursor 1 space to the right of the question mark. Now the
computer waits, cursor blinking, for the operator to type in the
answer and press the <RETURN> key.
The word INPUT may be followed by any text contained in quote
marks (""). This text is PRINTed on the screen, followed
by the question mark.
After the text comes a semicolon (;) and the name of one or
more variables separated by commas. This variable is where the
computer stores the information that the operator types. The variable
can be any legal variable name, and you can have several different
variable names, each for a different input.
EXAMPLES of INPUT Statement:
100 INPUT A
110 INPUT B, C, D
120 INPUT "PROMPT"; E
When this program RUNs, the question mark appears to prompt
the operator that the Commodore 64 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 hits <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 the <RETURN>, Commodore 64 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.
The INPUT statement can never be used outside a program. The
Commodore 64 needs space for a buffer for the INPUT variables,
the same space that is used for commands.
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