一个是采取Windows里面的ActiveX Script控件！
另外可以参考CSDN的ZsWang写的代码：
调用：
Calc('3+3+1')看看？
ZsWang
//完整代码
uses
Math;
procedure Bracket(mText: string; var nLStr, nCStr, nRStr: string);
var
L, R: Integer;
I: Integer;
B: Boolean;
begin
nLStr := '';
nCStr := '';
nRStr := '';
B := True;
L := 0;
R := 0;
for I := 1 to Length(mText) do
if B then begin
if mText = '(' then
Inc(L)
else if mText = ')' then
Inc(R);
if L = 0 then
nLStr := nLStr + mText
else if L > R then
nCStr := nCStr + mText
else B := False;
end else nRStr := nRStr + mText;
Delete(nCStr, 1, 1);
end; { Bracket }
function Calc(mText: string): string;
var
vText: string;
function fCalc(mText: string): string;
var
vLStr, vCStr, vRStr: string;
I, J, K, L: Integer;
begin
L := Length(mText);
if Pos('(', mText) > 0 then begin
Bracket(mText, vLStr, vCStr, vRStr);
Result := fCalc(vLStr + fCalc(vCStr) + vRStr);
// ~
end else if (Pos('+', mText) > 0) or (Pos('-', mText) > 0) then begin
I := Pos('+', mText);
J := Pos('-', mText);
if I = 0 then I := L;
if J = 0 then J := L;
K := Min(I, J);
vLStr := Copy(mText, 1, Pred(K));
vRStr := Copy(mText, Succ(K), L);
if vLStr = '' then vLStr := '0';
if vRStr = '' then vRStr := '0';
if I = K then
Result := FloatToStr(StrToFloat(fCalc(vLStr)) + StrToFloat(fCalc(vRStr)))
else Result := FloatToStr(StrToFloat(fCalc(vLStr)) - StrToFloat(fCalc(vRStr)))
end else if (Pos('*', mText) > 0) or (Pos('/', mText) > 0) then begin
I := Pos('*', mText);
J := Pos('/', mText);
if I = 0 then I := L;
if J = 0 then J := L;
K := Min(I, J);
vLStr := Copy(mText, 1, Pred(K));
vRStr := Copy(mText, Succ(K), L);
if vLStr = '' then vLStr := '0';
if vRStr = '' then vRStr := '0';
if I = K then
Result := FloatToStr(StrToFloat(fCalc(vLStr)) * StrToFloat(fCalc(vRStr)))
else Result := FloatToStr(StrToFloat(fCalc(vLStr)) / StrToFloat(fCalc(vRStr)))
end else if Pos('_', mText) = 1 then
Result := FloatToStr(-StrToFloat(fCalc(Copy(mText, 2, L))))
else Result := FloatToStr(StrToFloat(mText));
end;
var
I, L: Integer;
begin
vText := '';
L := Length(mText);
for I := 1 to L do
if (mText = '-') and (I < L) and (not (mText[Succ(I)] in ['+', '-', '(', ')'])) then
if (I = 1) or ((I > 1) and (mText[Pred(I)] in ['*', '/'])) then
vText := vText + '_'
else if ((I > 1) and (mText[Pred(I)] in ['+', '-'])) or
((I > 1) and (mText[Pred(I)] = ')') and (I < L) and
(not (mText[Succ(I)] in ['+', '-', '(', ')']))) then
vText := vText + '+_'
else vText := vText + mText
else vText := vText + mText;
Result := fCalc(vText);
end; { Calc }
