music programming text book



    This subchapter looks at loops.

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stub section

    This subchapter is a stub section. It will be filled in with instructional material later. For now it serves the purpose of a place holder for the order of instruction.

    Professors are invited to give feedback on both the proposed contents and the propsed order of this text book. Send commentary to Milo, PO Box 1361, Tustin, California, 92781, USA.

loops or repetition

    A loop or repetition is the act of repeating an action or actions. A lot of the power of computers is being able to do repetitive choices over and over (sometimes millions or more times).

    This is one of the most important and powerful features of a computer — the ability to repeatedly do something over and over in really large numbers of repetitions.

    The Iterative DO LOOP is perfomed the exact number of times the programmer specified.

    The DO WHILE loop is perfomed zero or more times.

    The DO UNTIL loop is perfomed at least once.

    The key difference between the DO WHILE loop and the DO UNTIL loop is that the condition test comes at the beginning of the DO WHILE loop and the condition test comes at the end of the DO UNTIL loop.

    The DO WHILE loop might never be performed (if the test condition fails before the first attempt to loop).

    The DO UNTIL loop will always be performed at least once (because the condition test occurs after the first pass of the loop).


    “26 The loop statement provides the basic iterative mechanism in the language. A loop statement specifies that a sequence of statements is to be executed repeatedly as directed by an iteration scheme, or until an exit statement is encountered.” —:Ada-Europe’s Ada Reference Manual: Introduction: Language Summary See legal information


    The following material is from the unclassified Computer Programming Manual for the JOVIAL (J73) Language, RADC-TR-81-143, Final Technical Report of June 1981.

    1.1.6 Flow of Control

    Loop-statements are used to repeat a sequence of statements.
    Here is an example of a loop-statement:

         FOR I:0 BY 1 WHILE I<1000;
            VAL = INPUT;
            IF VAL < 0;
            GIVEN(I) = VAL;

    This statement uses the function INPUT to get an input value and
    assigns that value to VAL.  It assigns input values to GIVEN(1),
    GIVEN(2), GIVEN(3), and so on until either GIVEN(999) has been
    assigned or a negative input is encountered.  The examples uses
    an EXIT statement, which causes immediate exit from the enclosing

    JOVIAL also has a form of loop that has just the WHILE clause; it
    can be used when the loop does not require an index.  Many
    calculations can be written as a while loop (which keeps going
    until some end condition is met) that encloses a case-statement
    (which selects the proper action for each time through the loop).

    Chapter 1 Introduction, page 11


   “18. A program without a loop and a structured variable isn’t worth writing.” —Alan Perlis, Epigrams on Programming, ACM’s SIGPLAN Notices Volume 17, No. 9, September 1982, pages 7-13

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free music player coding example

    Coding example: I am making heavily documented and explained open source code for a method to play music for free — almost any song, no subscription fees, no download costs, no advertisements, all completely legal. This is done by building a front-end to YouTube (which checks the copyright permissions for you).

    View music player in action:

    Create your own copy from the original source code/ (presented for learning programming).

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free computer programming text book project

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    Created: October 31, 2010

    Last Updated: October 17, 2012

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