[rarratia]

Empezado por darkone2k3

Gracias roman por responder, voy a investigar lo que me dices.
Salu2 desde Chile.

Estimado, la función Eval para delphi es fácil, aquí va:

Código Delphi [-]
function Eval(const expression : string) : extended;
var
  pos : Integer;
  ch : char;
  function GetChar : char;
  begin
    if pos < Length (expression) then
    begin
      Inc (pos);
      ch := expression [pos]
    end
    else ch := #0;
    result := ch
  end;
  function GetNonWhitespace : char;
  begin
    repeat
      GetChar
    until not (ch in [' ', #9]);
    result := ch
  end;
  function CalcAddition : extended; forward;
  function CalcNumber : extended;
  var
    s : string;
    gotPoint : boolean;
  begin
    gotPoint := False;
    while ch in ['0'..'9'] do
    begin
      s := s + ch;
      if (GetChar = '.') and not gotPoint then
      begin
        s := s + ch;
        GetChar;
        gotPoint := True
      end
    end;
    result := StrToFloat (s)
  end;
  function CalcExpressionInBrackets : double;
  begin
    result := CalcAddition;
    if ch = ')' then
      GetChar
    else
      raise Exception.Create ('Missing '')'' in expression')
  end;
  function CalcTerm : extended;
  begin
    case ch of
      '0'..'9' : result := CalcNumber;
      '(' : result := CalcExpressionInBrackets;
      else raise Exception.Create ('Syntax error in expression')
    end
  end;
  function CalcSignedTerm : extended;
  begin
    case GetNonWhitespace of
      '+' : result := CalcSignedTerm;
      '-' : result := -CalcSignedTerm;
      else result := CalcTerm
    end
  end;
  function CalcPower : extended;
  begin
    result := CalcSignedTerm;
    while ch = '^' do
      result := exp (ln (result) * CalcSignedTerm)
  end;
  function CalcMultiplication : extended;
  begin
    result := CalcPower;
    while ch in ['*', '/'] do
      case ch of
        '*' : result := result * CalcPower;
        '/' : result := result / CalcPower
      end
  end;
  function CalcAddition : extended;
  begin
    result := CalcMultiplication;
    while ch in ['+', '-'] do
      case ch of
        '+' : result := result + CalcMultiplication;
        '-' : result := result - CalcMultiplication
      end
  end;
begin
  pos := 0;
  result := CalcAddition
end;