85 lines
2.3 KiB
Plaintext
85 lines
2.3 KiB
Plaintext
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Expression evaluation library v1.0 - by lone
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--------------------------------------------
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How to use
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~~~~~~~~~~
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¦ resetVars
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-----------
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void resetVars(void);
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Resets the variables table. It is necessary to call it prior to evaluate your first
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expression or variables contents may be random instead of zero
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¦ evaluate
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----------
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double evaluate(char *expression, int *col);
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Evaluates an expression and returns the result.
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If a syntax error was encountered during the parsing of the expression, then col will
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be non-null and col-1 will be the index of the char which triggered the error.
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Limitations
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~~~~~~~~~~~
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¦ you can set only up to 1024 variables.
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¦ only decimal and hexadecimal bases available
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¦ operators are limited to :
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+ - / * % & |
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¦ functions are limited to :
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sin, cos, tan,
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asin, acos, atan,
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atan2, sqr, sqrt,
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pow, exp, log, log10
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Some examples
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~~~~~~~~~~~~~
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- assignments :
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pi=3.1415927
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a=atan2(cos(pi/4),2)
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- direct evaluations :
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cos(pi/4)
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sin(45)
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- base notations :
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3bh (this is 0x3B)
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17d (this is 17)
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17dh (this is 0x17D)
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Adding new functions
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~~~~~~~~~~~~~~~~~~~~
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The file EVAL.C contains the functions table (fnTable). Just add an entry with the name,
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the number of parameters, and a pointer to the function body. Implement the body and
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you're done. If your function ahs more than 2 parameters, you'll need to extend the grammar
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description file (CAL.Y) to add the FUNCTION3 (and eventually subsequent) token(s) and
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parsing informations.
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SCAN.L & CAL.Y
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~~~~~~~~~~~~~~
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SCAN.L contains description for the lexical analyzer generator (LEX). Use makel.bat to rebuild
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LEXTAB.C
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CAL.Y contains the LALR formal grammar description for the parser generator (BISON). Use makey.bat
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to rebuild CAL_TAB.C
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Compiling
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~~~~~~~~~
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Just include all source files to your project, and include EVAL.H into your main source code.
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