
                        Chapter 1 - Getting Started


                          WHAT IS AN IDENTIFIER?

             Before you can do anything in any language, you must at
        least know how to 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 some compilers, 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 may be  permitted
        by your 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 C is defined, up to 32 significant characters can be
             used  and  will  be  considered  significant  by   most
             compilers.   If  more than 32 are used,  they  will  be
             ignored by the compiler.

                         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
        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


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                        Chapter 1 - Getting Started


        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 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  your  C  compiler  is
        properly  loaded and operating.  If you have  any  problems,
        the COMPILER.DOC file may have help for your compiler.  Even
        if  it doesn't have help for your particular  compiler,  the
        notes  on another compiler may be helpful for yours since  C
        compilers tend to have many things in common.

                     A DISCUSSION OF SOME OF THE FILES

                                  CCL.BAT

             This  file,  which does not exist on  the  distribution
        disk,  is the batch file that calls in an editor,  then  the
        compiler (pass 1 and pass 2, if it exists), and finally runs
        the resulting compiled program.  There are several  examples
        of  batch  files which can be used  with  various  compilers
        given  in  the  "COMPILER.DOC"  file  on  the   distribution
        diskette.   It is up to you to type in a batch file for  use
        with  your particular compiler, considering also the  method
        required to call in your editor.  To use it, simply type the
        batchfile  name with the desired filename.  After typing  in
        your particular CCL.BAT file, try it by typing CCL  FIRSTEX.


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                        Chapter 1 - Getting Started


        You will get the sourcefile displayed on the monitor by your
        editor.   If you don't have one of the compilers  listed  in
        the  "COMPILER.DOC" file, you will have to modify the  batch
        file  to  accomodate your compiler.  Note that  if  you  are
        using  Turbo C, you can use the Integrated  Environment  and
        you will not need a batch file.  The same is true if you are
        using  Microsoft Quick-C, it has its own built in  operating
        environment so you will not need a batchfile.

             If you have a hard disk available, it will be up to you
        to  modify the batch file to use the hard disk.   Note  that
        most of the batch files have statements to erase the  object
        files  and  executable files after use to prevent  the  disk
        from  filling up with unecessary files after a  program  has
        served its purpose.

             Even though you will have a lot of files to compile and
        run, you will find that a suitable batch file will help  you
        to get through the steps quickly and with little typing.

                                  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 C, you will have  the
        ability  to  read and understand the source  code  for  this
        program.

                                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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