I would like to readln an equation, for example: 5*9-2/3, or whatever,
including reserved pascal words for example: "sqr","sqrt","cos","sin", ect.
Then I would like to use it in my program in calculating the answer.

If there is a(n) (easy) way of doing this, please let me know...

Look for Pedt Scragg's parser and some more. Even a very old
TP 3 example is there, the MicroCalc spreadsheet program,
which has such a parser.

http://www.geocities.com/SiliconValley/2926/tp.html

 149061 Jul 19 1998 ftp://garbo.uwasa.fi/pc/link/tsfaqp.zip
 tsfaqp.zip Common Turbo Pascal Questions and Timo's answers, linked

   All the best, Timo

....................................................................
Prof. Timo Salmi   Co-moderator of news:comp.archives.msdos.announce
Moderating at ftp:// & http://garbo.uwasa.fi/ archives 193.166.120.5
Department of Accounting and Business Finance  ; University of Vaasa
mailto:t...@uwasa.fi <http://www.uwasa.fi/~ts/>  ; FIN-65101,  Finland

Daniel Corbier, UCALC
http://www.ucalc.com

If you have BP7, there is the possibility of reading the line(s),
writing a file with suitable head and tail and your lines in between,
then using EXEC on BPC to compile the file into a DLL, then loading the
DLL dynamically.  It /should/ work; and, once it works at all, it gives
immense expressive power.

Alternatively, http://www.merlyn.demon.co.uk/programs/longcalc.pas,
which is still in development, already can read in expressions in RPN
and evaluate them.  Transcendentals are not included : it is a long
integer program, capable of thousand-digit arithmetic.  By entering #f9
one executes what is in effect a pre-written RPM program.  You could
alter the storage from kilodigits to extended and add new routines.

NOTE : In it, #uf, #sd, #ds, whilst plausible, are not yet correct.

One thing to remember with this is that you should look for "sqrt"
before "sqr" or untoward effects happen with your calculation.

There's an example of a parser that will do this available via
http://www.pedt.demon.co.uk/

--
Pedt Scragg                    <newsmas...@pedt.demon.co.uk>

[Expression-Compiler (OOP/TP55-TP70)]
<http://home.t-online.de/home/Antivivisektion/math.pas>

You may use it like in my example below:

|  Uses Math;
|  Var E: Expression; Term: String; Result: Float;
|  Begin
|    Write('Enter expression: ');
|    ReadLn(Term);
|    Result := E.EvaluateTerm(Term);
|    Write('Result: ',Result:0:20);
|  End.

You may also use one-char variables to evaluate complex expressions:

|  Uses Math;
|  Var E: Expression; X: Word;
|  Begin
|    E.Init;
|    E.Parse := '2*X+SIN(X)*TAN(X/8)';
|    E.FormatTerm;
|    E.Compile;
|    For X := 1 To 100 Do
|    Begin
|      E.Data['X'] := X;
|      E.PrintResult; { same as WriteLn(E.FormFloat(E.Evaluate)); }
|    End;
|  End.

The expression may be as complex as you wish,
with 25 build-in var's A-Z (like in basic).

It's even possible to add your own functions at runtime, e.g. RANDOM:

|  Uses Math;
|  Var E: Expression; X: Word;
|  
|  {$F+} Function MyFunc (x: Float): Float; {$F-}
|  Begin
|    MyFunc := Random(Round(x));
|  End;
|  
|  Begin
|    E.Init; { Insert ADDFUNC after this line }
|    E.AddFunc('RANDOM',MyFunc);
|    { Now you can use RANDOM(...) in your expressions, example: }
|    E.Parse := 'RANDOM(100)';
|    E.FormatTerm;
|    E.Compile;
|    E.PrintResult;
|  End.

The error-handling (simple HALT) has to be worked out...

--
              ---===Coders Against Vivisection===---

A.E.Neumann fr die Antivivisektion e.V., PO-Box 201, D-53569 Unkel
mailto:Antivivisekt...@t-online.de http://Antivivisektion.base.org/

I only arrived home just now (I'm at boarding school). But yes, please,
could you post your source code for me to work from... It would really be a
great help. If not, you could simply e-mail it to me.

Thanks so much...

A la Grange, Aliwal North, South Africa