(octave.info)Terminal Input

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14.1.2 Terminal Input
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Octave has three functions that make it easy to prompt users for input.
The ‘input’ and ‘menu’ functions are normally used for managing an
interactive dialog with a user, and the ‘keyboard’ function is normally
used for doing simple debugging.

 -- : ANS = input (PROMPT)
 -- : ANS = input (PROMPT, "s")
     Print PROMPT and wait for user input.

     For example,

          input ("Pick a number, any number! ")

     prints the prompt

          Pick a number, any number!

     and waits for the user to enter a value.  The string entered by the
     user is evaluated as an expression, so it may be a literal
     constant, a variable name, or any other valid Octave code.

     The number of return arguments, their size, and their class depend
     on the expression entered.

     If you are only interested in getting a literal string value, you
     can call ‘input’ with the character string "s" as the second
     argument.  This tells Octave to return the string entered by the
     user directly, without evaluating it first.

     Because there may be output waiting to be displayed by the pager,
     it is a good idea to always call ‘fflush (stdout)’ before calling
     ‘input’.  This will ensure that all pending output is written to
     the screen before your prompt.

     See also: Note: yes_or_no, Note: kbhit,
     Note: pause, Note: menu, *note listdlg:
     XREFlistdlg.

 -- : CHOICE = menu (TITLE, OPT1, ...)
 -- : CHOICE = menu (TITLE, {OPT1, ...})
     Display a menu with heading TITLE and options OPT1, ..., and wait
     for user input.

     If the GUI is running, the menu is displayed graphically using
     ‘listdlg’.  Otherwise, the title and menu options are printed on
     the console.

     TITLE is a string and the options may be input as individual
     strings or as a cell array of strings.

     The return value CHOICE is the number of the option selected by the
     user counting from 1.  If the user aborts the dialog or makes an
     invalid selection then 0 is returned.

     This function is useful for interactive programs.  There is no
     limit to the number of options that may be passed in, but it may be
     confusing to present more than will fit easily on one screen.

     See also: Note: input, Note: listdlg.

 -- : ANS = yes_or_no ("PROMPT")
     Ask the user a yes-or-no question.

     Return logical true if the answer is yes or false if the answer is
     no.

     Takes one argument, PROMPT, which is the string to display when
     asking the question.  PROMPT should end in a space; ‘yes-or-no’
     adds the string ‘(yes or no) ’ to it.  The user must confirm the
     answer with <RET> and can edit it until it has been confirmed.

     See also: Note: input.

   For ‘input’, the normal command line history and editing functions
are available at the prompt.

   Octave also has a function that makes it possible to get a single
character from the keyboard without requiring the user to type a
carriage return.

 -- : kbhit ()
 -- : kbhit (1)
     Read a single keystroke from the keyboard.

     If called with an argument, don’t wait for a keypress.

     For example,

          x = kbhit ();

     will set X to the next character typed at the keyboard as soon as
     it is typed.

          x = kbhit (1);

     is identical to the above example, but doesn’t wait for a keypress,
     returning the empty string if no key is available.

     See also: Note: input, Note: pause.