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Program EasyEvalExample;
{
Copyright (c) 2011 by Marco van de Voort(marco@freepascal.org)
member of the Free Pascal development team
See the file COPYING.FPC, included in this distribution,
for details about the copyright. (LGPL-with-static-linking-exception)
Rock bottom example of new evaluator helper function.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
}
{$mode delphi}
Uses Symbolic,Classes,sysutils;
var s : AnsiString;
a : extended;
b : integer;
begin
// quickevaluate('expression',[],[]); evaluates a constant expression to an
// extended result
s:='(5+5+10)*2';
writeln(s,'=',QuickEvaluate(s,[],[]):10:1);
// ... but still allows variables:
a:=2.0;
b:=3;
s:='(5+A+10)*B';
// variable names are case sensitive!
writeln(s,'=',QuickEvaluate(s,['A','B'],[a,b]):10:1,' with A=',a:0:1,' and B=',b);
// now let's do that again, but add a symbol (C) that we don't define:
try
a:=2.0;
b:=3;
s:='(5+A+10)*B+C';
// variable names are case sensitive!
writeln(s,'=',QuickEvaluate(s,['A','B'],[a,b]):10:1,' with A=',a:0:1,' and B=',b);
except
on E:Exception do
Writeln('An exception occured: ',e.message);
end;
end.
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