                Introduction to the TURBO Pascal Tutorial


            Assuming  you know nothing at all about Pascal,  and  in 
        fact,  that  you  may  know  nothing  about  programming  in 
        general,  we will begin to study Pascal.  If you are already 
        somewhat  familiar  with programming and especially  Pascal, 
        you  will  probably want to skip very  quickly  through  the 
        first few chapters.   You should at least skim the first few 
        chapters,   and  you  should  read  the  remainder  of  this 
        introduction.

            A  few  comments are in order to get us started  in  the 
        right direction.   The sample programs included on the disks 
        are  designed to teach you the basics of Pascal and they  do 
        not  include any clever or tricky code.   Nearly all of  the 
        programs  are  really  quite  dumb as far  as  being  useful 
        programs,  but  all  will teach one or  more  principles  of 
        Pascal.   I  have seen one tutorial that included a 12  page 
        program  as  the first example.   In fact there were only  2 
        example programs in the entire tutorial.   I will completely 
        bypass any long programs until the very end of this tutorial 
        in order to illustrate concepts used in Pascal  programming.  
        It  will then be very easy for you to use the tools  learned 
        to build as large a program as you desire.

            Due  to  the fundamental design of the Pascal  language, 
        certain words are "reserved" and can only be used for  their 
        defined purposes.   These are listed on page 37 of the TURBO 
        PASCAL  manual (version 3.0 will be used in all references).  
        All  of  the sample programs are written with  the  reserved 
        words  in  all capital letters,  and the user  variables  in 
        lower case.   Don't worry about what reserved words are yet, 
        they will be completely defined later.

            Another  problem I have noticed in example  programs  is 
        the  use of one word for all definitions.   For  example,  a 
        sort program is stored in a file called SORT, the program is 
        named SORT, and various parts of the program are referred to 
        as SORT1,  SORT2, etc.  This can be confusing since you have 
        no  idea  if  the  program  name must be  the  same  as  the 
        filename, or if any of the other names were chosen to be the 
        same  because of some obscure rule not  clearly  documented.  
        For  this  reason,   the  example  programs  use  completely 
        arbitrary  names whenever the choice of a name adds  nothing 
        to  the  readability  or  clarity  of  a  program.    As  an 
        illustration of this,  the first program is named puppy_dog.  
        This  adds  nothing to the understanding of the program  but 
        does  illustrate that the program name means nothing to  the 
        Pascal compiler concerning what the program does.

            What is a compiler?   There are two primary methods used 
        in  running  any  computer  program that  is  written  in  a 



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                Introduction to the TURBO Pascal Tutorial


        readable   form  of  English.    The  first  method  is   an 
        interpreter.  An interpreter is a program that looks at each 
        line of the "English" program, decides what the "English" on 
        that line means, and does what it says to do.  If one of the 
        lines  is  executed  repeatedly,  it  must  be  scanned  and 
        analyzed each time, greatly slowing down the solution of the 
        problem  at  hand.   A compiler,  on the other  hand,  is  a 
        program  that looks at each statement one time and  converts 
        it into a code that the computer understands directly.  When 
        the compiled program is actually run,  the computer does not 
        have to figure out what each statement means,  it is already 
        in a form that the computer can run directly,  hence a  much 
        faster execution of the program.

                   PREPARATION FOR USE OF THIS TUTORIAL.

             Copy the example files onto your TURBO working disk and 
        you  are  ready to begin,  provided of course that you  have 
        already  learned  how to start the TURBO system and  how  to 
        edit a Pascal file.   Be sure you make a backup copy of  the 
        Pascal  tutorial disks so you cannot accidentally  lose  all 
        information  on  the distribution disks.   You  should  read 
        Chapter  1 of the TURBO Pascal reference manual to be  ready 
        to  use this tutorial.   You should be familiar with use  of 
        the editor supplied with TURBO Pascal before beginning.

            If  you are not using TURBO Pascal,  you will  still  be 
        able  to  compile  and execute most of these  Pascal  files, 
        since  most  of the examples use "standard"  Pascal.   There 
        will  be  some  statements used which are  unique  to  TURBO 
        Pascal and will probably not work with your compiler.   This 
        will  be  especially true when you come to  the  chapter  on 
        standard input and output since this is where most compilers 
        differ.   Unfortunately,  this  is one of the most important 
        aspects of any programming language, since it is required to 
        get data into and out of the computer to do anything useful.

            It  is  highly  suggested that you  do  the  programming 
        exercises  after  you complete the study for  each  chapter.  
        They  are carefully selected to test your  understanding  of 
        the material covered in each chapter.   If you do not write, 
        enter,  debug,  and  run  these programs,  you will only  be 
        proficient  at  reading Pascal.   If you  do  the  exercises 
        completely,  you  will  have a good start at being a  Pascal 
        program writer.

            It should also be mentioned that this tutorial will  not 
        teach  you  everything  you  will ever need  to  know  about 
        Pascal.   You will continue to learn new techniques as  long 
        as  you continue to write programs.   Experience is the best 



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                Introduction to the TURBO Pascal Tutorial


        teacher here just as it is in any endeavor.   This  tutorial 
        will  teach you enough about Pascal that you will feel  very 
        comfortable  as you search through the reference manual  for 
        some  topic.   You will also be able to read and  understand 
        any Pascal program you find in textbooks or magazines.

            When you are ready, I will meet you in Chapter 1.














































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