Variables can be assigned interactively with the read(varname)
function. A number is expected to be typed in the terminal window, and
-- if valid -- is assigned to the variable varname.
The function read_string()does the same for strings, but is
only allowed as an argument to other functions.
Output to the controlling terminal can be made with the familiar
printf(format, ...) call. It behaves just like in ''C'', see
e.g. man printf for details.
Input and Output of arrays or text-events to files can be accomplished by the functions listed in 5.3.