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<H1>Four Function Calculator</H1>

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<H2>Introduction</H2>
<P>
          <tt>ffcalc.syn</tt> implements a simple four function
          calculator. The
          calculator has 52 registers, labeled 'a' through 'z' and 'A'
          through 'Z'. <tt>ffcalc</tt> evaluates arithmetic expressions and
          assignment statements and prints the results. The
          expressions may contain '<CODE>+</CODE>', '<CODE>-</CODE>',
          '<CODE>*</CODE>', and '<CODE>/</CODE>' operators as
          well as parentheses. In addition, <tt>ffcalc</tt> supports
          the free
          use of white space and C style comments in the input. It
          also includes syntax error handling, including a diagnostic
          message, and resynchronization.
<P>
          <tt>ffcalcmx.syn</tt> is a simple variation on
          <tt>ffcalc.syn</tt>. The only
          difference between the two grammars is that <tt>ffcalcx</tt> uses a
          deliberately ambiguous grammar for expressions, with
          precedence statements to resolve the ambiguities.
<P>

<H2>Building FFCALC</H2>
          To build a working copy of <tt>ffcalc</tt>, you need to
          carry out the following steps:
<UL>
<LI>      1.  Run Anagram and build a parser for <tt>ffcalc.syn</tt>. </LI>
<LI>      2.  Using your C compiler, compile and link <tt>ffcalc.c</tt>. </LI>
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<H2>Running FFCALC</H2>
          <tt>ffcalc</tt> reads expressions and assignment statements from
          stdin. You may either type input directly, or provide input
          by using file redirection. The file <tt>test.ffc</tt> has been
          provided as a sample.
<P>
          Run <tt>ffcalc</tt> from the command line and type an
          arithmetic expression or assignment
          statement to be evaluated. <tt>ffcalc</tt> will accept addition,
          subtraction, multiplication and division operations, as well
          as unary negation, using floating point arithmetic. It
          respects the conventional order of operations and allows the
          use of parentheses to override the natural order of
          computation. You may use spaces, tabs, and C-style comments
          freely. You may use variable names consisting of a single
          upper or lower case letter.
<P>
          Each expression or assignment statement must be terminated
          by a newline. Note that <tt>ffcalc</tt>, unlike
          <tt>rcalc</tt>, does not explicitly check
          for division by zero.
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<ADDRESS><FONT SIZE="-1">
                  AnaGram parser generator - examples<BR>
                  Four Function Calculator<BR>
                  Copyright &copy; 1993-1999, Parsifal Software. <BR>
                  All Rights Reserved.<BR>
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author	David A. Holland
date	Mon, 13 Jun 2022 00:40:23 -0400
parents	13d2b8934445
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