Search                        Top                                  Index

HELP REPEAT                           Aaron Sloman, September 1978

The word REPEAT is one way of building a loop in POP-11. The statement

    repeat <number> times <actions> endrepeat;

causes the <actions> to be performed the appropriate <number> of times;
e.g.

    repeat 4 times pr(".") endrepeat;

will print four dots (see HELP *PR).

    [% repeat 66 times "cat" endrepeat %] =>

will make a list containing 66 occurrences of the word "cat" and print
it out (see HELP *PERCENT).

    repeat 4 times
        draw(5);
        turn(90);
    endrepeat;

will cause the turtle to draw a 5 by 5 square (see HELP *TURTLE).

    repeat 5*x times
        repeat y + z times pr(".") endrepeat;
        pr(newline)
    endrepeat;

will print out 5 times X lines of dots, each line containing Y + Z dots.

For an indefinite loop use

    repeat
        [isnt this boring] =>
    endrepeat;

This will produce an indefinite loop, which may be terminated by
*RETURN, *QUITIF, *QUITUNLESS, or *QUITLOOP.

A loop can be restarted with *NEXTLOOP, *NEXTIF, *NEXTUNLESS

You can also execute a procedure a fixed number of times by using
*SYSREPEAT. For example:

    sysrepeat(5, vedcharup);

See also HELP
    *SYSREPEAT - procedure for calling "repeat" syntax - useful for closures
    *LOOPS   - for other types of iteration
    *FOREVER - use of FOREVER in iteration

See also
    REF * SYNTAX,  * POPSYNTAX

--- C.all/help/repeat --------------------------------------------------
--- Copyright University of Sussex 1987. All rights reserved. ----------