Programming 265
the Otcombination (press and hold O, then
press
t, then release both keys). Pressing O
stops the interaction with the terminal.
There are also commands for outputting data in the
Graphics section. In particular, the commands TEXTOUT
and TEXTOUT_P can be used for test output.
This example prompts the user to enter a value for the
radius of a circle, and prints the area of the circle on the
terminal.
EXPORT AREACALC()
BEGIN
LOCAL radius;
INPUT(radius, "Radius of Circle",:"r =
","Enter radius",1);
PRINT("The area is " + *radius^2);
END;
Notice the use of the LOCAL variable for the radius, and
the naming convention that uses lower case letters for the
local variable. Adhering to such a convention will
improve the readability of your programs.
GETKEY Syntax: GETKEY
Returns the ID of the first key in the keyboard buffer, or -1
if no key was pressed since the last call to GETKEY. Key
IDs are integers from 0 to 50, numbered from top left (key
0) to bottom right (key 50) as shown on the following
page.
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