Chapter 1 - Getting Started


                          WHAT IS AN IDENTIFIER?

             Before you can do anything in any language, you must at
        least  know  how you name an identifier.  An  identifier  is
        used  for any variable, function, data definition, etc.   In
        the  programming language C, an identifier is a  combination
        of alphanumeric characters, the first being a letter of  the
        alphabet or an underline, and the remaining being any letter
        of  the alphabet, any numeric digit, or the  underline.   In
        the  case of Turbo C, a dollar sign is permitted but not  as
        the first character of an identifier.  It should be  pointed
        out that even though a dollar sign is permitted by the Turbo
        C  compiler, it is not used anywhere in this tutorial  since
        it  is not in general use by C programmers, and is not  even
        allowed by most compilers.  If you do not plan to write  any
        portable  code, you can use it at will if you feel it  makes
        your code more readable.

             Two rules must be kept in mind when naming identifiers.

        1.   The  case  of  alphabetic  characters  is  significant.
             Using  "INDEX" for a variable is not the same as  using
             "index"  and  neither  of them is  the  same  as  using
             "InDeX"  for a variable.   All three refer to different
             variables.

        2.   As Turbo C is defined, up to 32 significant  characters
             can  be  used and will be considered  significant.   If
             more  than  32 are used, they will be  ignored  by  the
             compiler.  You can reduce the number used  to  anything
             less  than 32 if you desire as a compiler option.   You
             should  not do this for the duration of your  study  of
             this  tutorial  as  you could  get  some  odd  compiler
             diagnostics.

                         WHAT ABOUT THE UNDERLINE?

             Even  though  the  underline can be used as part  of  a
        variable  name, and adds greatly to the readability  of  the
        resulting  code,  it  seems  to  be  used  very  little   by
        experienced   C  programmers.   It  adds  greatly   to   the
        readability  of  a  program to  use  descriptive  names  for
        variables  and  it  would be to your  advantage  to  do  so.
        Pascal  programmers tend to use long descriptive names,  but
        most C programmers tend to use short cryptic names.  Most of
        the  example programs in this tutorial use very short  names
        for that reason.

             Any computer program has two entities to consider,  the
        data,  and  the program.   They are highly dependent on  one
        another  and  careful planning of both will lead to  a  well


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                        Chapter 1 - Getting Started


        planned and well written program.   Unfortunately, it is not
        possible  to study either completely without a good  working
        knowledge of the other.  For this reason, this tutorial will
        jump  back  and forth between teaching  methods  of  program
        writing  and  methods of data  definition.    Simply  follow
        along and you will have a good understanding of both.   Keep
        in  mind that,  even though it seems expedient to  sometimes
        jump right into the program coding,  time spent planning the
        data  structures  will be well spent and the  final  program
        will reflect the original planning.

                        HOW THIS TUTORIAL IS WRITTEN

             As  you go through the example programs,  you will find
        that  every  program  is complete.   There  are  no  program
        fragments that could be confusing.   This allows you to  see
        every  requirement that is needed to use any of the features
        of  Turbo  C as they are presented.  Some tutorials  I  have
        seen give very few, and very complex examples.  They  really
        serve  more  to confuse the student.  This tutorial  is  the
        complete  opposite  because  it strives to  cover  each  new
        aspect  of programming in as simple a context  as  possible.
        This  method, however, leads to a lack of knowledge  in  how
        the  various parts are combined.  For that reason, the  last
        chapter is devoted entirely to using the features taught  in
        the  earlier  chapters. It will illustrate how  to  put  the
        various features together to create a usable program.   They
        are given for your study, and are not completely  explained.
        Enough details of their operation are given to allow you  to
        understand how they work after you have completed all of the
        previous lessons.

             At this point, you should load and run FIRSTEX.C if you
        have  not yet done so, to see that the Turbo C  compiler  is
        properly  loaded and operating.  If you have  any  problems,
        see  the COMPILER.DOC file for help in properly  setting  up
        your computer to compile and run Turbo C programs.

                     A DISCUSSION OF SOME OF THE FILES

                                  LIST.EXE

             This  file will list the source files for you with line
        numbers  and  filename.   To  use  it,  simply  type  "LIST"
        followed by the appropriate filename.   Type LIST  FIRSTEX.C
        now  for  an example.   The C source code is given later  in
        Chapter 14 along with a brief description of its operation.
        After  you  have completed your study of Turbo C,  you  will
        have the ability to read and understand the source code  for
        this program.



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                        Chapter 1 - Getting Started


                                PRINTALL.BAT

             This is a batch file that will call the above  LIST.EXE
        file  once for each of the example C programs,  printing all
        of  the  files out.   If you want a hardcopy of all  of  the
        files,  enter PRINTALL and watch as your printer fills about
        150 sheets of paper with C programs.














































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